by
Joseph William Corsello
Bachelor of Science
University of New Hampshire, 2011
Submitted to the Department of Civil and Environmental Engineering in Partial Fulfillment of the Requirements for the Degree of
Master of Engineering in Civil and Environmental Engineering at the
Massachusetts Institute of Technology MASSACHUSETTS iNSTITUTE
OF TECHNOLOGY
June 2014 JUN 1 3 2014
@2014 Joseph William Corsello. All Rights Reserved.
The author hereby grants to MIT permission to reproduce and distribute publicly paper and electronic copies of this thesis document in whole or in part in any medium now known or hereafter created.
Signature of Autf or:
Certified by:
,
Accepted by:

by
Joseph William Corsello
Submitted to the Department of Civil and Environmental Engineering on May 9, 2014 in Partial
Fulfillment of the Requirements for the Degree of
Master of Engineering in Civil and Environmental Engineering at the
Massachusetts Institute of Technology
ABSTRACT
Vapor intrusion is the vapor-phase migration of volatile organic compounds (VOCs) into buildings due to subsurface soil or groundwater contamination. Oxygen replenishment rates beneath a building are significant for quantifying potential contaminant degradation rates within the vadose zone. Additionally, the migration of VOC soil gas vapors into buildings is partly due to pressure differences between the building and the subsurface.
This study addresses these issues through two laboratory scale experiments. The Wind
Experiment quantifies oxygen replenishment rates as a function of above ground wind speed, while the Depressurization Experiment examines the flow rate of air into a model building as a function of decreased building pressure. For the Wind Experiment, tests were run for basement and slab-on-grade building configurations, as well as with and without a simulated sidewalk. Results show that increased above ground wind speed increases the oxygen replenishment rate and that the presence of a simulated sidewalk inhibits the oxygen replenishment rate. For the Depressurization Experiment, tests were again run for basement and slab-on-grade building configurations, as well as for two different foundation crack percentages. Results of the experiment indicate that increased building vacuum increases the flow rate of air into the building. In addition, basement configuration, increased foundation crack percentage, or some combination of the two results in increased airflow into the building. Additional research is needed for both experiments in order to obtain statistically significant results and resolve remaining uncertainties. Specific research needs include an improved wind source, additional monitoring locations, various sidewalk sizes and shapes, and different foundation crack configurations.
Thesis Supervisor: David E. Langseth
Title: Senior Lecturer of Civil and Environmental Engineering

ACKNOWLEDGEMENTS
I would like to thank Dr. David Langseth, Dr. Atul Salhotra, Dr. Eric Adams and the rest of the MEng staff, Steven Rudolph, Jessica Friscia and the rest of the Course 1 MEng Class of
2014, Dr. Nancy Kinner, Dr. James Malley, Dr. Robin Collins, Kara Connolly, and my parents, without whom none of this would have been possible.
Joseph William Corsello
Cambridge, Massachusetts
May 2014
5

6

TABLE OF CONTENTS
1 In tro d u ctio n ......................................................................................................................................................
1 .1 B a ck g ro u n d ............................................................................................................................................
1.2 Literatu re R eview ...............................................................................................................................
1.3 Stu dy A p p roach ...................................................................................................................................
2 M ethods .......... ........... ............... . ..... ..................................
2.1 M aterials ........................ ........... ............ .
.......
..........
...................
.
.................. 17
............................
17
1 1
1 1
13
15
2.1.1 Sand ........................................ ...... ...............................................
2.1.2 Sand Box and Building................. .....................
2.1.3 Differential Pressure Transducers ........... ...
17
19
....................
20
2.1.4 Data Acquisition System............... ................
2.1.5 Propeller Fan ............................. .............
........
20
..... 21
2.2
2.1.6 Peristaltic Pumps .............................................
Procedures.............. .... .
...................
2.2.1 Building Configuration Naming Scheme ....................
21
.. ......................................
22
....... 22
2.2.2 Barometric Pressure Readings ................................... 22
2.2.3 Differential Pressure Transducer Calibration. ................
2.2.4 Wind Experiment................ .............
........23
................ 23
2.2.4.1 Building Configurations ..........
2.2.4.2 Wind Speeds ............................................
.
... .................................
24
24
2.2.4.3 Data Collection.................................. .........
29
2.2.5 Depressurization Experiment.... .
.. ........
2.2.5.1 Building Configurations ........... ........ ........ ........... 32
2.2.5.2 Data Collection.................... ....... ................ 34
2.2.5.3 Building Depressurization .................................. 37
2.2.6 Apparatus Disassembly.... .
.
.
...
3 Results .... ..................
3.1 Wind Experiment .
.......................
.
.... .... .. ..... .........................................
42
.........-...........42
3.1.1 Data Reduction ................... .............................
42
3.1.2 Total Hydraulic Head .. ...... .
.
....... ................-..... 42
3.1.3 Isopotential Contours ........... ...... .........................
55
3.1.4 Oxygen Replenishment Rate . ......................... ............
55
3.2 Depressurization Experiment........................... ..............
57
7

3.2.1 D ata R ed u ction .............................................................................................................................
3.2.2 Total Hydraulic Head .................................................................................................................
3.2.3 Isopotential Contours ................................................................................................................
3.2.4 Airflow Into Building..................................................................................................................71
4 D iscu ssio n ..........................................................................................................................................................
4.1 W ind Experiment................................................................................................................................73
4.1.1 W in d Sp eed s ..................................................................................................................................
4.1.2 Building Configuration..............................................................................................................74
4.1.2.1 Basement versus Slab-On-Grade.............................................................................
4 .1 .2 .2 Sid ew alk ..................................................................................................................................
4.2 Depressurization Experiment ...................................................................................................
4.2.1 Building Depressurization...................................................................................................75
4.2.2 Building Configuration........................................................................................................
4.2.2.1 Basement versus Slab-On-Grade.............................................................................
4.2.2.2 Foundation Crack ................................................................................................................
5 Additional Research Considerations................................................................................................
6 C o n clu sio n s........................................................................................................................................................8
7 R e fe re n ce s..........................................................................................................................................................8
5 7
57
71
7 3
7 3
74
7 4
75
79
1
2
76
76
76
LIST OF FIGURES
Figure 1 Summary of Grain Size Analysis ............................................................................................. 18
Figure 2 - Boston W ind Rose ............................................................................................................................
Figure 3 Measured Wind Speed for BAS and BAS_SW at 10 ft/s...................
25
26
Figure 4 Measured Wind Speed for BAS and BAS_SW at 15 ft/s................... 26
Figure 5 Measured Wind Speed for BAS and BAS_SW at 20 ft/s................... 27
Figure 6 Measured Wind Speed for SOG and SOGSW at 10 ft/s ................... 27
Figure 7 Measured Wind Speed for SOG and SOGSW at 15 ft/s ...................
Figure 8 Measured Wind Speed for SOG and SOGSW at 20 ft/s ...................
28
28
Figure 9 W ind Experiment: Basement Side View............................................................................. 29
Figure 10 W ind Experiment: Basement Back View.......................................................................... 29
Figure 11 W ind Experiment: Slab-On-Grade Side View .............................................................. 30
Figure 12 W ind Experiment: Slab-On-Grade Back View .............................................................. 30
8

Figure 13 Wind Experiment: Basement Monitoring Locations................................................. 31
Figure 14 Wind Experiment: Slab-On-Grade Monitoring Locations ........................................ 31
Figure 15 Depressurization Experiment: 0.5% Foundation Crack Configuration....... 33
Figure 16 Depressurization Experiment: 0.08% Foundation Crack Configuration...... 33
Figure 17 Depressurization Experiment: Basement Side View.................................................. 34
Figure 18 Depressurization Experiment: Basement Back View ................................................ 34
Figure 19 Depressurization Experiment: Slab-On-Grade Side View........................................ 35
Figure 20 Depressurization Experiment: Slab-On-Grade Back View....................................... 35
Figure 21 Depressurization Experiment: Basement Monitoring Locations ......................... 36
Figure 22 Depressurization Experiment: Slab-On-Grade Monitoring Locations................ 36
Figure 23 -
Figure 24 -
Oxygen Replenishm ent Rates................................................................................................
A irflow Into B u ilding....................................................................................................................
57
7 2
Figure 25 Pressure Transducer 1 Calibration.................................................................................. 97
Figure 26 Pressure Transducer 2 Calibration..................................................................................
Figure 27 Untransform ed Data Exam ple................................................................................................100
98
Figure 28 Log-Transform ed Data Exam ple ........................................................................................... 100
LIST OF TABLES
T able 1 G rain Size A nalysis.............................................................................................................................
Table 2 Building Configuration Naming Scheme ............................
Table 3 Barometric Pressures........... ..... .... .............
...... Table 4 Peristaltic Pump Flow rates...................
Table 5 Average Building Pressures............ ........
Table 6 BAS_10 ft/s Total Hydraulic Head ..................
..........
........
......................
...........
22
......
38
40
................. 43
Table 7 BAS_15 ft/s Total Hydraulic Head ............................
Table 8 BAS_20 ft/s Total Hydraulic Head ...................................
17
....... 44
45
46 Table 9 BASSW_10 ft/s Total Hydraulic Head................................
Table 10 BASSW_15 ft/s Total Hydraulic Head.............................. 47
Table 11
Table 12
-
-
BASSW_20 ft/s Total Hydraulic Head...............................
SOG_10 ft/s Total Hydraulic Head...................... .............
48
49
50 Table 13 SOG_15 ft/s Total Hydraulic Head..................................
Table 14 SOG_20 ft/s Total Hydraulic Head........................... ......... 51
9

Table 15 SOG_SW _10 ft/s Total Hydraulic Head...............................................................................
Table 16 SOG_SW_15 ft/s Total Hydraulic Head...............................................................................
Table 17 SOG_SW _20 ft/s Total Hydraulic Head...............................................................................
Table 18 Oxygen Replenishment Rates................................................................................................
Table 19 BAS_0.08%_10.9 Pa Total Hydraulic Head .......................................................................
Table 20 BAS_0.08% _19.4 Pa Total Hydraulic Head.......................................................................
Table 21 BAS_0.08%_27.2 Pa Total Hydraulic Head.......................................................................
Table 22 BAS_0.5%_5.84 Pa Total Hydraulic Head..........................................................................
Table 23 BAS_0.5% _10.1 Pa Total Hydraulic Head..........................................................................
Table 24 BAS_0.5% _13.8 Pa Total Hydraulic Head..........................................................................
Table 25 SOG_0.08%_18.5 Pa Total Hydraulic Head.......................................................................
Table 26 SOG_0.08%_35.6 Pa Total Hydraulic Head.......................................................................
Table 27 SOG_0.08%_49.3 Pa Total Hydraulic Head.......................................................................
Table 28 SOG_0.5% _8.45 Pa Total Hydraulic Head..........................................................................
Table 29 SOG_0.5%_14.8 Pa Total Hydraulic Head..........................................................................
Table 30 SOG_0.5% _20.6 Pa Total Hydraulic Head..........................................................................
Table 31 Airflow Into Building ......................................................................................................................
Table 32 Calculated Hydraulic Conductivities..................................................................................
61
62
63
64
65
56
59
60
52
53
54
66
67
68
69
70
72
92
10

1.1 Background
Vapor intrusion is the vapor-phase migration of volatile organic compounds (VOCs) into buildings due to subsurface soil or groundwater contamination. The vapor intrusion pathway can cause potential human exposure to VOCs and result in-adverse health effects.
The contaminants of interest related to vapor intrusion are typically petroleum hydrocarbons (PHCs) or chlorinated hydrocarbons (CHCs), though the pathway is applicable to any volatile chemical. The vapor intrusion pathway can potentially result in concentrations of VOCs in indoor air that exceed the human health-based indoor air regulatory concentrations, set by the United States Environmental Protection Agency
(USEPA). Additionally, methane and certain other volatile chemicals can pose explosion hazards when they accumulate in confined spaces in the presence of oxygen at levels between the upper and lower explosion limit (UEL and LEL) (EPA 2013a, b).
The USEPA issued the first set of draft guidance documents (EPA 2001, 2002) in 2001 and
2002 to address the issue of vapor intrusion and offer guidance on how to manage a vapor intrusion site. These draft documents provided guidance for the investigation and management of vapor intrusion at Resource Recovery and Conservation Act (RCRA),
Superfund, and Brownfield sites, but did not address vapor intrusion for petroleum releases at underground storage tank sites (Kalmuss-Katz 2013). Several proposed revisions (EPA 2013a, b) to the draft guidance documents have been released for comment with the intention to have them finalized in 2013. To date these have not been finalized. In addition, beginning in the 2000s, several states began to develop their own guidance
11

documents, in many cases consistent with the federal guidance. Today, a majority of states have adopted some form of a vapor intrusion regulatory program (Levy 2013).
If there is reason for suspicion of the vapor intrusion pathway at a site, an investigation is required per federal guidance. Practical experience with assessing vapor intrusion has demonstrated that this pathway can be extremely challenging to assess (Swartjes et al.
2011). Typically, indoor air regulatory levels are low (on the order of micrograms per cubic meter), so extra care must be taken to avoid contamination during sampling. Certain contaminants may also be detected in air inside buildings due to emissions from the use of consumer products, building materials, and outdoor air sources, thus the contribution from the subsurface may be difficult to determine. Furthermore, indoor air concentrations of
VOCs vary with season, location, weather, life-style, and building ventilation rate. These issues contribute to a high level of uncertainty and variability when assessing the potential and degree of vapor intrusion (Swartjes et al. 2011).
This variability in indoor air concentrations and the large number of controllable and uncontrollable factors that affect indoor air concentrations can lead to unnecessary remediation costs. The uncertain nature of vapor intrusion investigations and analyses can predict a greater contribution to indoor air from vapor intrusion than actually exists.
Mitigation strategies and technologies (e.g., sub-slab depressurization, soil vapor extraction, vapor barriers) are relatively inexpensive when compared to performing extensive investigations (Swartjes et al. 2011). Depending on site conditions, mitigating vapor intrusion in the absence of sufficient data may be more cost effective than completely
12

evaluating the pathway through extensive data collection and negotiating with the various stakeholders, including the regulatory agencies.
To obtain an estimate of the vapor intrusion pathway, scientists and engineers often measure subsurface soil, soil vapor, or groundwater concentrations and use a computational model to predict an attenuation factor (a). The attenuation factor, a dimensionless factor, is the ratio of the indoor air concentration to the sub slab concentration. The models used to predict the attenuation factor heavily rely on several assumptions and often result in a relatively inaccurate analysis (Swartjes et al. 2011).
Additional research on the vapor intrusion pathway is needed to create a more reliable and accurate model.
1.2 Literature Review
The physical transport of soil gas through the vadose zone and into basements has been studied in both the field and laboratory, but is still not fully understood. It is commonly assumed that under natural conditions, soil vapor diffusion dominates the migration of
VOCs through unsaturated soils (Johnson et al. 1998). However, the major contributor to soil vapor entry into basements is often thought to be dominated by advection caused by the depressurization of buildings (Swartjes et al. 2011). There are many ways in which depressurization of buildings occurs including the "stack effect," temperature differences between the building and outdoor air, barometric pressure variations, pressure differentials created by wind loads against a building, and the operation of heating ventilation air condition (HVAC) systems (Sakaki et al. 2011).
13

Studies have been conducted to quantify these methods of depressurization and the factors that affect these processes. A subset of the relevant literature includes studies of the effects of soil moisture and temperature (Sakaki et al. 2011), atmospheric pressure fluctuations
(Robinson at al. 1997), soil type and stratigraphy (Escobar et al. 2010), and basement floor integrity (Fischer et al. 1996). Based on these studies, the most important factors affecting the migration of soil vapor are soil properties such as moisture content and permeability, as well as pressure fluctuations within the building. Using the critical soil properties in combination with physical environmental conditions, general analytical transport models describing soil vapor transport in the subsurface have been quantified, as described in the this literature.
In addition to the physical transport of soil vapor in the vadose zone, biodegradation rates of subsurface contaminants are an important factor in determining the attenuation factor.
Especially in the case of PHC contamination where aerobic conditions enhance the biodegradation process, the rate at which oxygen is replenished in the subsurface is an important factor that has not been extensively studied or quantified. To gain a better understanding of the oxygen replenishment rate beneath a full-scale house, Lundegard et al. (2008) performed field studies and modeled the migration of nitrogen and oxygen in unsaturated soil. This study concluded that strong winds (>3 meters per second) increased the oxygen replenishment rate, while an increase in soil moisture due to the infiltration of rainwater decreased this replenishment rate. In addition, the spatial and temporal oxygen data suggest rapid replenishment immediately below the building slab followed by downward diffusion of oxygen.
14

1.3 Study Approach
This study examines subsurface flow of air beneath a model building through two laboratory experiments. The Wind Experiment is intended to quantify the oxygen replenishment rate beneath a building due to variations in above ground wind speed. The
Depressurization Experiment models how air flows into a building as a result of negative pressures within the building.
The Wind Experiment was intended to address the transport of oxygen below a building on a VOC-impacted property. Properties contaminated with VOCs as a result of leaking fuel storage tanks, or other sources can cause indoor air contamination as a result of vapor intrusion. Depending on the type of VOC of concern, oxygen may promote (in the case of
PHCs) or inhibit (CHCs) the degradation process of these compounds in the subsurface.
The rate at which atmospheric oxygen is transported beneath a building is significant for the biodegradation rate of VOCs and thus the potential for vapor intrusion. The Wind
Experiment further evaluates the findings of Lundegard et al. (2008) that strong winds experienced above ground increase the rate at which oxygen is transported in the subsurface.
In addition, depressurization within a building also increases the potential for vapor intrusion by influencing the magnitude and direction of advective soil gas intrusion into a basement (Fischer et al. 1996). There are many parameters that cause depressurization within a building including HVAC systems, temperature gradients, and barometric pressure changes. However, the relative contributions of advection by these parameters are not well
15

understood (Lundegard et al. 2008). The Depressurization Experiment provides additional research on subsurface airflow into a model building due to building depressurization.
16

2 Methods
The following sections discuss the materials used and procedures of the study.
2.1 Materials
2.1.1 Sand
The experiments utilized clean, kiln-dried Quikrete All-Purpose sand.
A grain size distribution analysis was performed on the sand using a RO-TAP mechanical sieve machine
(Photo 1 in Appendix D) in accordance with ASTM C136 (ASTM Standard C136). The results of the grain size analysis are shown in Table 1 and Figure 1.
Table 1 Grain Size Analysis
Measurements Overload ing Check Results
Sieve Sieve Mass of Mass of Mass of Sieve Accumulated Percent
Number Opening Sieve Soil + Sieve Retained Limit
(mm) (g m) (gim) Soil (gm) (9m)
% Retained Finer
(%)
(%)
8
20
40
2.36
0.85
0.43
528.6
410.6
574.6
532.20
426.60
600.90
3.60
16.00
26.30
211.0
76.0
38.0
4.2
23.1
54.0
95.8
76.9
46.0
60
80
100
Pan
0.25
0.18
0.15
0.00
529.6
430.7
540.3
377.3
550.10
439.70
543.70
383.50
20.50
9.00
3.40
6.20
22.4
15.8
13.4
0.0
78.1
88.7
92.7
100.0
21.9
11.3
7.3
0.0
17

100
90
80
70
60
S50
40
30
2 20
10
0
10.000
-
1.000
Particle Diameter (mm)
-
0.100
Figure 1 Summary of Grain Size Analysis
Based on the grain size analysis, the sand used in this study is classified as poorly graded sand (SP) according to the Uniform Soil Classification System (ASTM Standard D2487). The sand had a porosity of approximately 0.29, which was calculated by adding a known amount of water to a representative sample of the sand. This process is further described in Appendix A.2 and is shown in Photo 2. The hydraulic conductivity of the sand (1.7x10
4 meters per second [m/s]) was obtained via a constant head test in accordance with ASTM -
D2434 (ASTM Standard D2434). A photo of the apparatus is shown in Photo 3 in Appendix
D. An in-depth description of this process is included in Appendix A.3 along with the conversion to conductivity of air (1.05x105 m/s) and calculation of intrinsic permeability
(1.7x10-" M 2
).
18

2.1.2 Sand Box and Building
The experiments were conducted in a three-quarter inch thick plywood box (4 feet long, 2 feet wide, 1 foot tall) filled with approximately eight cubic feet of the sand. A one cubic foot simulated building structure (building) was constructed of three-quarter inch thick plywood that was glued and screwed together to create a near-air tight seal. The size of the building was intended to simulate a small, two-story building with approximate footprint area of 625 square feet (1:25 scale). See Appendix A.1 for an in-depth description of scaling the model building. The building was placed four inches below the top of the sand to simulate a basement condition, and placed on top of the sand for slab-on-grade configuration. A small piece of wood was also placed on the sand in front of the building to simulate a sidewalk. For more information regarding the various experiments and building configurations, refer to Sections 2.2.4 and 2.2.5. For the depressurization experiment,
3/16" diameter holes were drilled in the bottom of the building to simulate cracks that are found within the concrete slab of a building. The holes promoted airflow from the porous media to the building so differential pressure readings could be recorded beneath the building. This study utilized two different percentages (0.08% and 0.5%) of "cracks" in the foundation. The orientations of the holes are described in Section 2.2.5.1. The calculation of crack percentage is available in Appendix A.4. It should be noted that round holes were used rather than straight cracks because scaling down straight cracks to laboratory scale would have created considerable edge effects (Fischer et al. 1996). Although round holes cause different patterns of air flow than thin cracks, this difference is small compared to the large edge effects of a thin crack on a laboratory scale (Fisher et. al. 1996).
19

2.1.3 Differential Pressure Transducers
The specifications of the differential pressure transducers used in this experiment
(Freescale Semiconductor) are available in Appendix G. On one end, the transducers were connected to wiring harnesses, which connected to the data acquisition module. Two pieces of 7/32" outer diameter flexible poly tubing (ClearFlex 60, Flex Tubing Products) were connected to the opposite end of the transducers. One piece was connected to a 14inch long piece of 3/16-inch stainless steel welded tubing (McMaster Carr) installed at various locations in the box, while the other piece was left open to the atmosphere in an undisturbed location to reduce the chance of pressure interference. The stainless steel tubing was installed to the desired locations described in Section 2.2.4.1 and 2.2.5.1 prior to filling the tank with sand in order to help minimize the chance of void spaces and preferential pathways to occur. In total, ten transducers were available for use. However, after initial testing, some significant variability was discovered in the various transducers.
For this reason, only one or two transducers were used during the experiments to help ensure instrument consistency.
2.1.4 Data Acquisition System
The data acquisition system (DAS) used in this study consisted of an IOTech Personal Daq
56 data acquisition module connected to a desktop computer equipped with Acqlipse Data
Acquisition software. The data acquisition module was comprised of an analog-to-digital
(A/D) converter connected to a sequential sampling multiplexer. A total of ten ports were wired to the multiplexer, allowing a maximum of ten devices to be used at one time. The differential pressure transducers were provided with approximately five volts of electricity, as recommended by the transducer specifications (see Appendix G). As the
20

transducers experienced pressure fluctuations, output voltages were sent from the transducers to the A/D converter via the multiplexer, which were then displayed real-time on the desktop computer software. The input voltage was also recorded on a separate port and then sent to the computer. The software was set to achieve optimum accuracy and precision in voltage readings for the expected output voltage readings and was set to collect a reading once per second during each test. Photo 4 shows the components of the
DAS, while Photo 5 shows a screenshot of the software interface.
2.1.5 Propeller Fan
Wind was created using a Dayton propeller fan (model 4UX61J) placed at one end of the experimental tank. A variable frequency drive (Variac, General Radio Company) was connected to the fan to allow consistent control of the wind speed. Further discussion of how wind speeds were obtained is provided in Section 2.2.4.2. At higher wind speeds, a large amount of turbulence created by the fan was experienced during the experiment. A discussion of this air turbulence is presented in Section 5.
2.1.6 Peristaltic Pumps
Two Cole Palmer Instruments Co. peristaltic pumps (models 7015-02 and 7015-72) were used to depressurize the building. Masterflex controllers connected to the pumps allowed for the airflow rate to be controlled manually. These flow rates are discussed further in
Section 2.2.5.3 and 3.2.4. Photo 7 shows the peristaltic pumps and how they were connected to the building. The process of varying the building vacuum is described in
Section 2.2.5.3.
21

2.2 Procedures
The experimental procedures are described in the following sections.
2.2.1 Building Configuration Naming Scheme
A total of eight different building configurations were used during this study. Table 2 provides brief descriptions of each configuration and its corresponding name used throughout the study.
Table 2 Building Configuration Naming Scheme
Description Test Name
Basement
Basement with Sidewalk
Slab-On-Grade
Slab-On-Grade with Sidewalk
Basement with 0.08% of Foundation Crack
Slab-On-Grade with 0.5% of Foundation Crack
BAS
BASSW
SOG
SOGSW
BAS 0.08%
Basement with 0.5% of Foundation Crack BAS_0.5%
Slab-On-Grade with 0.08% of Foundation Crack SOG 0.08%
SOG_0.5%
2.2.2 Barometric Pressure Readings
Throughout the duration of this study, barometric pressure readings were recorded at the beginning and end of each test using a wireless advanced weather station (Ambient
Weather WS-1171A). Although the transducers used in this study measured differential pressure, and the barometric pressure should not theoretically have an effect on the results, barometric pressure was recorded in order to obtain a complete set of data for the study. The barometric pressure readings are provided in Table 3.
22

Test
BAS
BAS SW
SOG
SOG SW
BAS 0.08
BAS 0.5
SOG_0.08
SOG_0.5
Table 3 Barometric Pressures
Barometric Pressure (kPa)
Start End Change
102.17
100.58
99.97
99.73
100.58
100.34
99.73
99.59
1.59
0.24
0.24
0.14
102.78
101.96
103.01
102.68
101.83
102.98
0.1
0.13
0.03
102.98 102.84 0.14
Overall, barometric pressure remained fairly constant throughout the study. Note that these barometric pressures were not used in any calculations performed as part of this study.
2.2.3 Differential Pressure Transducer Calibration
Prior to beginning the experiments, the differential pressure transducers were calibrated using the apparatus shown in Photo 6. The pressure reading from the transducer was recorded simultaneously with the measured difference in the water column. A linear data fit was applied to the transducer and water column readings to develop an equation to convert the transducer output of volts to kilopascals (kPa) for each transducer. Appendix
A.5 further describes the transducer calibration process.
2.2.4 Wind Experiment
The Wind Experiment examines the flow of air beneath a small building induced by simulated wind conditions. To monitor the flow of air within the porous media, differential
23

pressure readings were collected at various locations beneath the building at different wind speeds.
2.2.4.1 Building Configurations
Four different building configurations were used in this experiment. For basement conditions (BAS), the building was placed four inches below the top of the sand. A 1-foot
by 3.5 inch piece of wood three-quarter inch thick wood was placed upwind of the building to simulate a sidewalk attached to a building (BASSW). These same configurations were applied to the slab-on-grade conditions (SOG; SOGSW), where the building was placed at the surface of the sand. Photos 8 through 12 show the various building configurations.
2.2.4.2 Wind Speeds
A variable frequency drive (VFD) was connected to the propeller fan to allow for various wind speeds to be achieved consistently. Three different average wind speeds were tested during the wind experiment (approximately 10 feet per second [ft/s], 15 ft/s, and 20 ft/s).
These values were chosen based on the average wind speeds experienced in Boston,
Massachusetts (Windfinder.com). A wind rose for Boston is shown in Figure 2.
24

NW
NNW
10
N
NNE
NE
WNW ENE
W E
WSW ESE
SW SE
SSW SSE
S
Source: Windfinder.com
Figure 2 Boston Wind Rose
Higher wind speeds would have been ideal; however the propeller peaked at approximately 20 ft/s. Due to the turbulent and inconsistent flow of air created by the fan, wind speeds were recorded at various locations on the building using a handheld anemometer (LaCrosse, EA-30104). The average speeds and locations are shown on Figure
3 through Figure 8.
25

242
2'
Figure 3 - Measured Wind Speed for BAS and BASSW at 10 ft/s
45.
Figure 4 - Measured Wind Speed for BAS and BASSW at 15 ft/s
26

2447
T2-JL6'
197
Figure 5 - Measured Wind Speed for BAS and BASSW at 20 ft/s
69.8
6r
8..2 FS .9
Z
Figure 6 - Measured Wind Speed for SOG and SOGSW at 10 ft/s
27

34
*4 .8
3
14.4
3.
13.8112.8-1
3-
Figure 7 - Measured Wind Speed for SOG and SOGSW at 15 ft/s
17.1
1.1901
11 .7
20.0+
Figure 8 - Measured Wind Speed for SOG and SOGSW at 20 ft/s
28

2.2.4.3 Data Collection
Differential pressure data was collected individually at each monitoring location with a single transducer at a rate of one reading per second. Schematics of the apparatus including monitoring locations for basement and slab-on-grade configuration are shown on
Figure 9 through Figure 14.
Propeller Fan
Sand
Differential pressure transducer location
Figure 9 - Wind Experiment Basement Side View
Data acquisition system
Differential pressure transducer
Stainless Steel Tubing
Figure 10 - Wind Experiment: Basement Back View
29

Propeller Fan
29 40 60 $0 1 IM0
It*70 9*0 t
Differential pressure transducer location
Figure 11 Wind Experiment: Slab-On-Grade Side View
Sand
I
Data acquisition system
Differential pressure transducer
I
I
ZZ
Stainless Steel Tubing
Figure 12 Wind Experiment: Slab-On-Grade Back View
30

15
S
I41
6'
3S
'5
15
3.
Z'.O
---------------------------------
3.
2.V
Is ft-
~~ 2S'
3.
3'
2S'
- -----
-
I
Is
S
---------
Figure 13 Wind Experiment: Basement Monitoring Locations
19
-
21
SL35
------------------
ZOO
-----a
3'.
1)IL b S -
t
3-
2-S
T,
- - - - - - - - - - - - - - - - - - - - - - - - - - - -
Figure 14 - Wind Experiment: Slab-On-Grade Monitoring Locations
At each location, a baseline of pressure data was recorded for approximately 90 seconds before setting the VFD and propeller fan to approximately 10 ft/s wind speed. The
31

pressure was allowed to reach a steady state prior to increasing the wind speed to 15 ft/s.
After the pressure readings stabilized a second time, the wind speed was increased to approximately 20 ft/s. Once a steady state was reached, the fan was turned off and the final baseline was recorded. This process was repeated at each location and for each building configuration.
2.2.5 Depressurization Experiment
The Depressurization Experiment examines the effect of negative pressure within a small building on the differential pressure beneath the building slab. To monitor these conditions, differential pressure was recorded both in the building and in the porous media beneath the building.
2.2.5.1 Building Configurations
Similar to the wind experiment, basement (BAS) and slab-on-grade (SOG) configurations were tested (see Photo 15 and 16). Within each configuration, two different building foundation integrities were tested. In one condition, 25 3/16-inch diameter holes were drilled in the bottom of the building in a symmetrical fashion (see Figure 15 and Photo 13).
This results in a total percentage of cracks in the foundation floor of approximately 0.5%
(BAS_0.5%; SOG_0.5%).
32

2.5"
2'
2.5"QQ
0
0
0 0 0
0
0
Figure 15 Depressurization Experiment: 0.5% Foundation Crack Configuration
For the second foundation condition, all but four of the holes were duct taped closed (see
Figure 16 and Photo 14) to create a total crack percentage of approximately 0.08%
(BAS_0.08%; SOG_0.08%). The calculation of basement crack percentage is available in
Appendix A.4.
2.5"
2"
2"0
2.5"
Figure 16 - Depressurization Experiment: 0.08% Foundation Crack Configuration
33

2.2.5.2 Data Collection
Differential pressure was recorded simultaneously in the building and at the various subsurface monitoring locations using two transducers at a rate of one reading per second.
Schematics of the apparatus including monitoring locations for basement and slab-ongrade configurations are shown on Figure 17 through Figure 22.
Silicon Tubing
Peristaltic
Pump 10170
20
60 79 so 90
100 110 120 130
160
Peristaltic
Pump
Figure 17 Depressurization Experiment: Basement Side View
Data acquisition system
Figure 18 - Depressurization Experiment: Basement Back View
34

Data acquisition system
Silicon Tubing
Peristaltic
Pump 10
20
9
3.
S. 11
1010 110
140
40
70
130
170
160
Peristaltic
Pump
Figure 19 - Depressurization Experiment: Slab-On-Grade Side View
I --"" I-
Figure 20 - Depressurization Experiment: Slab-On-Grade Back View
35

Z.
0
4-1
2.5"
2.5
2
2.5
2.,S'
2
Figure 21 - Depressurization Experiment: Basement Monitoring Locations
Zr
I" i's
A
I.s
3
Figure 22 - Depressurization Experiment: Slab-On-Grade Monitoring Locations
36

At each location, a baseline was recorded for approximately 60 seconds prior to turning on the peristaltic pumps to create a building vacuum. Following the baseline, one pump was turned on to full speed (17.4 cm 3 /s) and pressure readings were allowed sufficient time to stabilize. Once the pressure in the building and in the subsurface reached a steady state, the second pump was turned on to half speed (27.9 cm 3 /s). Again, once readings stabilized, both pumps were turned up to full speed (37.3 cm 3 /s) to create the final building vacuum.
Section 2.2.5.3 provides a discussion of the pump speeds and resulting building vacuums.
After stabilization, the pumps were turned off and the original baseline pressures were recorded. This process was repeated at each location and for each building configuration.
2.2.5.3 Building Depressurization
During the tests, two peristaltic pumps worked in parallel to depressurize the building to various vacuums, as shown in Photo 7. The silicon tubing of the pumps was connected to two-inch pieces of 3/16-inch outer diameter stainless steel welded tubing (McMaster Carr).
Each of the two pump speeds was set using a Masterflex controller. Three building pressures were tested during this experiment. Building pressures varied depending on the percentage of foundation crack and how flush the building was placed on the sand, making it difficult to set the building pressure at a consistent value for each run of each test.
Therefore, the settings on the peristaltic pump controllers remained consistent for each of the three building pressures for the duration of the experiment.
To calculate the approximate airflow rates at each of the three pump speeds tested, water was used in place of air. To gather this information, a volume of water was collected over a timed interval for each pump speed. The data for these test runs are shown in Table 4.
37

Table 4 Peristaltic Pump Flow rates
Pump Setting
Pump 1100%
Pump 1 100%
Pump 1100%
Plump 1 100%,
Pump 2 50%
Plump 1 100%,
Pump 2 50%
Plump 1 100%,
Pump 2 50%
Pump 1 100%,
Pump 2 100%
Pump 1 100%,
Pump 2 100%
Pump 1 100%,
Pump 2 100%
Pump 1 100%,
Pump 2 100%
Pump 1 100%,
Pump 2 100%
Volume
Collected (cm 3 )
265
172
174
276
Time (s) Flow rate Average Flow
(cm 3 /s) rate (cm 3 /s)
15
10
10
17.7
17.2
17.4
17.4
10 27.6
282 10 28.2 27.9
279 10 27.9
381
378
369
368
370
10
10
10
10
10
38.1
37.8
36.9
36.8
37
37.3
Theoretically, these average values calculated using water should be approximately equal to those of air due to the mechanical function of the peristaltic pumps. As the rotating shoe of the peristaltic pump passes along the tubing, a volume of fluid is isolated within the tubing, creating a strong vacuum towards the pump. Once the shoe completely passes along the tubing, the fluid volume is released. Although this volume within the tube is initially compressed, it is restored to its original volume once it is released. This action suggests that compressibility should not be a factor and that using water as a substitute fluid for air should result in approximately equivalent flow rates. Average building
38

vacuums resulting from these peristaltic pump flow rates for each of the experiments are provided in Table 5.
39

Note that the values listed are in units of Pascals and that the "Pressure Change in Building" row values are the differences in the average baseline and the average values at each peristaltic pump flow rate for each test. Building vacuums observed in real buildings range from 0 to 10 Pa (Hodgson 1992), but are typically 5 Pa or less (Fischer et al. 1996). The building vacuums in this study range from approximately 5.8 to 49 Pa. Two of the 12 vacuums were less than 10 Pa, six were between 10 and 20 Pa, and the remaining four were greater than 20 Pa
2.2.6 Apparatus Disassembly
Once all the necessary data for this study was collected, the experimental apparatus was disassembled. The reusable pieces of wood to make the box and building were unscrewed and returned to the MIT Course 1 undergraduate laboratory for potential future use. The pieces of wood deemed unusable in the future were discarded in accordance with the MIT
Environmental Health and Lab Safety Building 1 Chemical Hygiene Plan. The sand was placed into five-gallon buckets and was stored in the MIT Course 1 laboratories for potential future use.
41

3 Results
The following sections describe the results of the experiments and the procedures to obtain the results.
3.1 Wind Experiment
3.1.1 Data Reduction
The data collected from the data acquisition system was reduced to single representative values at each location for each condition tested. For example, an arithmetic average pressure value was calculated for basement configuration for the initial baseline, at 10 ft/s wind, at 15 ft/s wind, at 20 ft/s wind, and a final baseline at each monitoring location.
Appendix A.6 discusses the rationale for using arithmetic average values. As the wind speed was increased, it took approximately 70 seconds for the recorded pressures in the subsurface monitoring locations to stabilize. Data prior to this stabilization (gray shaded areas in the time series data plots in Appendix B.1) were not used to compute the representative values.
3.1.2 Total Hydraulic Head
These average representative pressure values were then used to calculate pressure head values at each location. Appendix A.7 provides an in-depth analysis of converting the pressure readings and the elevations from each location to total hydraulic head values.
Table 6 through Table 17 shows the pressure readings, elevations, and corresponding total hydraulic head values for each of the building configurations and wind speeds tested.
42

3.1.3 Isopotential Contours
In order to visualize and quantify the subsurface flow conditions, the computer software program SEEP/W 2012 by GEO-SLOPE International Ltd. was used. SEEP/W is a software product used for analyzing groundwater flow within porous media. In order to modify the model to match this specific study, the air conductivity calculated in Appendix A.3 was entered as the hydraulic conductivity of the fluid. Once this value was entered, the subsurface region was drawn to scale and total hydraulic head values listed in bold in Table
6 through Table 17 were entered at their corresponding monitoring locations. The model then drew isopotential contour lines based on the specified head values. These isopotential contours are provided in Appendix C.1, and their corresponding SEEP/W data reports are available in Appendix E. Note that SEEP/W extrapolates isopotential contours, so contours drawn in locations with no hydraulic head data should be considered highly uncertain.
3.1.4 Oxygen Replenishment Rate
In order to quantify the rate at which oxygen is replenished beneath a building, the Flux
Section tool in SEEP/W was used to calculate the total flow of air across a specified area.
To calculate the flow rate of air beneath the building, the Flux Section line was drawn directly downward from the upwind end of the house down to approximately three inches below the lowest monitoring locations. This accounts for all air transported into the 12 inch long by 12 inch wide by 8 inch deep target area, which was consistent for both basement and slab-on-grade building configurations. For this study, it is assumed that the area at which potential subsurface contamination exists is located directly below the outside edges of the building. Oxygen flux rates and oxygen replenishment rates were then calculated from these airflow rates into this simulated zone of contamination, as described
55

in Appendix A.8. Note that the airflow rates calculated from the Flux Section tool do not take into account the width of the experimental tank. To account for this, the given flow rates calculated by SEEP/W were multiplied by the tank width (two feet or 61 centimeters). Table 18 provides these airflow rates, the oxygen flux rates, and the oxygen replenishment rates. To further analyze these results, oxygen replenishment rate versus wind speeds scatter plots were formulated and are present in Figure 23. Section 4.1
provides a discussion of these results. Note that 1% per minute is equivalent to 1,440% per day.
Table 18 - Oxygen Replenishment Rates
Building
Configuration
BAS
BASSW
SOG
SOGSW
Wind Speed Flow rate Oxygen
3
(ft/s) (cm /s) Rate
(g/min)
10
15
20
10
15
20
10
15
20
10
15
20
3.02
5.34
6.58
1.84
3.38
4.40
3.01
5.16
6.90
1.75
2.74
3.49
0.05
0.09
0.11
0.03
0.06
0.07
0.05
0.09
0.12
0.03
0.05
0.06
% of Oxygen
Replenished per Minute
0.96%
1.70%
2.09%
0.59%
1.07%
1.40%
0.96%
1.64%
2.19%
0.56%
0.87%
1.11%
56

Oxygen Replenishment Rate
S0012,
L302t,
A 0U
2UB
HA
d L
Figure 23 -
Oxygen Replenishment Rates
3.2 Depressurization Experiment
3.2.1 Data Reduction
Similar to the Wind Experiment, arithmetic average representative pressure values were calculated for each test condition. Time series plots of the pressure readings collected in the building and in the subsurface are available in Appendix B.2. Again, gray areas on these plots indicate data that was excluded from the average data calculation due to equilibration time.
3.2.2 Total Hydraulic Head
The same process used in the Wind Experiment was used to calculate head values for the
Depressurization Experiment. Appendix A.7 describes the process by which the average pressure values and the elevations of each location were converted to total hydraulic head
57

values. Table 19 through Table 30 display the pressure data collected during the experiment, monitoring location elevations, and resulting total hydraulic head values for each test of the experiment.
58

3.2.3 Isopotential Contours
Using the same process described in Section 3.1.3, the total hydraulic head values listed in
Table 19 through Table 30 were entered into SEEP/W where isopotential contour diagrams were created for each test condition. The isopotential contour diagrams are available in Appendix C.2 and subsequent SEEP/W data reports are shown in Appendix E.
Similar to the Wind Experiment, isopotential contour extrapolations should be considered
highly uncertain due to lack of data in those regions.
3.2.4 Airflow Into Building
The total flow of air from the subsurface into the building was quantified by drawing
SEEP/W Flux Sections below the sand surface on both sides of the building. These locations theoretically capture the entire flow of air from the subsurface into the building assuming there is no leakage within the experimental tank. These airflow values
(multiplied by the two feet wide dimension not included from the Flux Section tool, as well as a factor of two to include airflow entering the building from all four sides) are tabulated in Table 31 and are graphically displayed with scatter plots in Figure 24. Table 31 also includes the measured peristaltic pump flow rates and the corresponding factor of difference between these and the SEEP/W flow rates. A discussion of these results is provided in Section 4.2.
71

BAS_0.5%
BAS_0.08%
SOG_0.5%
SOG_0.08%
Building
Pressure (Pa
5.84
10.1
13.8
10.9
19.4
27.2
8.45
14.8
20.6
18.5
35.6
49.3
Table 31 Airflow Into Building
Calculated Flow Peristaltic rate (cm
3
Flow rate (cm
3 /s)
Factor
Difference
14.29 17.4 1.2
23.27
32.46
13.98
20.77
27.07
11.39
17.46
23.53
10.77
27.9
37.3
17.4
27.9
37.3
17.4
27.9
37.3
17.4
1.4
1.5
1.6
1.2
1.1
1.2
1.3
1.6
1.6
15.81
21.42
27.9
37.3
1.8
1.7
LKJo
H
PI/
Flowrate Into Building
""
0.998
4 i.2 -, 86Ui. v t -d 3 , " " ,
E 20 0 x.D
i :, W
1000
5 00
/
4
/ix
+ 4 *114
09 91 1
*Bk~ b 0~
~(X U ~
30
Su~dng Vacm IP.)
Figure 24 Airflow Into Building
72

4 Discussion
4.1 Wind Experiment
4.1.1 Wind Speeds
Figure 23 depicts the relationship between the percent of oxygen replenished in the target area per minute and above ground wind speed. In general, it is clear that increased wind speed increases the rate at which oxygen is replenished in the target area, based on the positive slope of the best-fit lines for each experimental setup (BAS, BAS_SW, SOG,
SOGSW). The limited amount of data in this study does not allow for a statistically sound quantifiable relationship to be established between oxygen replenishment rate and above ground wind speeds, however the available data points are fairly linear based on their R 2 values, which range from 0.97 to 0.99. Examination of the isopotential contour diagrams suggests that there may be stagnant zones below the downwind edge of the building at lower wind speeds for basement building configuration, possibly resulting in decreased oxygen replenishment rates at these locations. For example, tests BAS and BASSW at 10 ft/s resulted in stagnant zones, while these zones did not appear for tests run at 15 and 20 ft/s. The extent of these stagnant zones should be considered approximate due to lack of data within these regions. In addition, the airflow rates and oxygen replenishment rates calculated in this experiment are most likely much larger than those that would be observed in the field. Factors that could decrease these rates include soil moisture content and soil stratigraphy (Sakaki et all. 2011, Escobar et al. 2010), both of which were idealized in this study. Section 5 addresses these data gaps and the need for further research.
73

4.1.2 Building Configuration
4.1.2.1 Basement versus Slab-On-Grade
Further examination of Figure 23 shows that there is not a large difference in the best-fit lines between the basement and slab-on-grade building configurations. The slope for BAS is 0.0011, while the slope for SOG is only slightly greater at 0.0012. This comparison is also somewhat true for the BASSW and SOGSW experiments (slopes of 0.0008 and 0.0006, respectively). There did not appear to be any significant qualitative trends between basement and slab-on-grade configurations upon examination of the isopotential contour diagrams.
4.1.2.2 Sidewalk
Based on the slopes of the best-fit lines in Figure 23 between BAS or SOG and their corresponding BASSW or SOGSW tests, it is fairly clear that the addition of a simulated sidewalk decreased the overall oxygen replenishment rate beneath the building to the target area. Both the slopes of the BAS (0.0011) and SOG (0.0012) tests are larger than that of the BASSW (0.0008) and SOGSW (0.0006) tests, respectively. Comparison of the isopotential contour diagrams for experiments with and without the simulated sidewalk further confirm this data as there appears to be a smaller hydraulic head gradient on the upwind side of the sidewalk experiments. It should be noted that this is a subjective qualitative analysis and no additional calculations were performed to confirm this hypothesis. A discussion of suggested methods to further quantify these results is presented in Section 5.
74

4.2 Depressurization Experiment
4.2.1 Building Depressurization
The data plotted in Figure 24 clearly indicates that increased building vacuum results in increased airflow into the building. This is evident based on the positive slopes of the best-
fit lines for the data. There is insufficient data to suggest statistical correlations, however this data suggests a linear relationship based on R 2 values all greater than 0.99. These calculated airflow rates should be considered idealized and real flow rates observed in the field would most likely be less due to soil moisture and soil stratigraphy. There does not appear to be any qualitative trends from examining the isopotential contour diagrams other than higher building pressures result in greater hydraulic head gradients beneath the building.
To perform a quality check on the airflow data produced by SEEP/W, these airflow rates were compared to the peristaltic pump flow rates measured using water. As shown in
Table 31, these two values are different by a factor ranging from 1.1 to 1.8. The following are possible reasons for these differences:
" The method of converting water flow rates to air flow rates through the peristaltic pumps may have included some error. There was no correction factor applied to either value, and since water and air have different physical properties, notability differences in compressibility, this may not be an entirely accurate assumption.
" As air was pumped from the building, a vacuum was created. The actual volumetric air flow rate may have been decreased due to the pressure difference between the
75

building and the atmosphere. The vacuum created in the building reduces the density of air, thus decreasing the total volume of air pumped.
* The analysis performed by SEEP/W was modified in order to match the laboratory setup. This modeling program is designed to characterize and model groundwater for full-scale sites. It is possible that in converting a full-scale groundwater site scenario to a laboratory-scale airflow scenario there is some potential for error.
4.2.2 Building Configuration
4.2.2.1 Basement versus Slab-On-Grade
Examination of Figure 24 suggests a possible relationship between basement and slab-ongrade building configuration. The slopes of the best-fit lines for BAS_0.5% (2.28) and
BAS_0.08% (0.803) tests are over two times greater than those of the SOG_0.5% (0.998) and SOG_0.08% (0.344) tests. One possible explanation for this difference is that the more sand surrounding the basement of the building created a better seal around the foundation holes, allowing for a higher vacuum to be achieved inside the building. When comparing the building vacuums produced at equal peristaltic pump speed settings, the basement configuration does appear to result in higher building vacuums. As discussed in the previous section, a higher building vacuum results in a greater airflow rate into the building. Examination of the isopotential contour diagrams does not provide any additional significant trends between basement and slab-on-grade configurations.
4.2.2.2 Foundation Crack
Figure 24 provides information that possibly suggests a decrease in percentage of foundation cracks results in decreased airflow into a building. Similar to basement versus
76

slab-on-grade, there appears to be a factor of approximately two difference between in the slopes of the airflow rate equations between basement crack percentages of 0.5% and
0.08% for both basement and slab-on-grade configurations. For example, the slope of
BAS_0.5% (2.28) is approximately double that of BAS_0.08% (0.803). A similar trend appears with the slab-on-grade tests (SOG_0.5% of 0.998 and SOG_0.08% of 0.344).
However, due to the similarities between this analysis of foundation crack percentage and the basement versus slab-on-grade analysis described in the previous section, it is unclear whether this difference in airflow into the building is a result of building configuration or foundation crack percentage.
Although there appears to be a fairly strong trend between foundation crack percentages, the data may not be entirely accurate based on the wide range of building vacuums experienced during the experiment. The results of test SOG_0.08% (slope of 0.344) are much lower than those of the other three tests. One possible reason why the results between SOG_0.08% and the rest of the experiments vary significantly could be because the building pressures for SOG_0.08% were much higher than the other experiments
(SOG_0.08% ran at building pressures of 18.5 to 49.3 Pa, while the rest ran from 5.84 to
27.2 Pa). A possible reason why the building pressures for SOG_0.08% were higher could be because there was less void space beneath the building as it was placed on the sand, creating a more airtight seal around the bottom of the building, thus increasing the vacuum potential inside the building. Examination of the isopotential contour diagrams for
BAS_0.08% suggests that this may have been true, as there appears to be one side of the building with higher head gradients. There may have been a void space on the opposite side of the building floor, which could result in a smaller gradient and possibly less flow of
77

air, assuming constant hydraulic conductivities. If this hypothesis is true, it may be seen that a smaller percentage of foundation crack could result in higher building pressures and a higher flow rate of air into the building.
78

5
In order to obtain a more complete and accurate set of data for future research on the topics discussed in this study, the following issues should be addressed:
" Use of a more powerful fan with perhaps a different blade configuration that is able to provide a more laminar flow of air. Based on the pressure data in the Wind
Experiment time series plots provided in Appendix B, as well as the wind speed figures in Figure 3 through Figure 8, it is clear that the propeller fan provided a turbulent flow of air during the study. As shown in the in the Wind Experiment time series plots, there is a high level of variability in the pressure readings, especially at higher wind speeds. For future research, it would be ideal to use a wind source that provides a more laminar flow, especially at higher wind speeds. This would decrease variability in the data, and perhaps provide more accurate results.
Additionally, a more powerful wind source could allow for a larger number of wind speeds to be analyzed, which could result in a more significant trend in the wind speed versus oxygen flux rate data.
* A larger apparatus with additional differential pressure monitoring locations. As a number of the isopotential contour diagrams were calculated, it became evident that additional data would have been useful to obtain a more complete understanding of subsurface conditions. A larger apparatus would also allow for the entire extent of the area of influence for both the Wind and Depressurization Experiments to be quantified. For the isopotential contour diagrams in this study, there is a large
79

amount of extrapolation calculated by SEEP/W. It would be ideal to have data that captures the entire zone of influence so no extrapolation would be necessary.
* For the Wind Experiment, it would be beneficial to vary the size and shape of the object used as the sidewalk. From the data collected in this study, there may be a trend that the simulated sidewalk reduces the amount of airflow beneath the building. Additional information that correlates the size and shape of the sidewalk and the amount of airflow in the subsurface could yield additional information that may be directly useful to sites impacted with subsurface contamination.
* During the Depressurization Experiment in this study, there may have been an inconsistency in how the building was placed on the porous media. As described in
Section 4.2.2.2, this inconsistency may be the reason why the airflow into the building results for SOG_0.08% does not correlate well with the rest of the tests.
Additional experimentation on this topic could potentially yield significant correlations between foundation crack and subsurface airflow.
" It would be beneficial to test different foundation crack configurations. For this experiment, only symmetrical configurations resulting in 0.5% and 0.08% of foundation crack were tested. Subsurface airflow patterns as a result of different foundation crack percentages, as well as different placement of the cracks (e.g., around the perimeter of the building footprint) could provide a more complete understanding of the effect foundation integrity has on the vapor intrusion pathway.
80

This study quantified the flow of air in porous media beneath a building due to above ground wind speed, building depressurization, and various forms of building configuration or construction through laboratory simulations. Relationships between these factors and the amount of air or oxygen flowing beneath the building were obtained and provide basic insight and understanding of airflow through porous media.
The primary findings from the Wind Experiment show that increased wind speed increases the rate at which oxygen is transported beneath a model building. Although there appears to be no significant quantifiable difference in basement versus slab-on-grade construction, the presence of a simulated sidewalk may decrease this oxygen replenishment rate.
Results from the Depressurization Experiment indicate increased subsurface airflow into the building due to increased building depressurization. There are still questions left unanswered regarding whether building configuration, foundation crack percentage, or some combination of the two is a major contributor to increased airflow in the model building.
The purpose of this study was to quantify the flow of air beneath a building susceptible to subsurface contamination. Although this study provides a basic understanding of these concepts, there are data gaps and additional research is needed to gain a complete understanding of the factors studied here.
81

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83

Wind-Tunnel Simulation of Transport and Dispersion About Buildings". Fluid
Mechanics and Wind Engineering Program, Department of Civil Engineering,
Colorado State University.
Plummer, Mitchell, Larry Hull, and Don Fox. 2004. "Transport of Carbon-14 in a
Large Unsaturated Soil Column." Vadose Zone
3: 109-21.
Robinson, Allen, and Richard Sextro. 1995. "Direct Measurement of Soil-Gas Entry into an Experimental Basement Driven by Atmospheric Pressure Fluctuations."
Geophysical Research Letters 22 (14): 1929-3 2.
-- . 1997. "Radon Entry into Buildings Driven by Atmospheric Pressure
Fluctuations." Environmental Science and Technology 31 (6): 1742-48.
Sakaki, Toshihiro, Paul Schulte, Abdullah Cihan, John Christ, and Tissa Illangasekare.
2011. "Airflow Pathway Development as Affected by Soil Moisture Variability in
Heterogeneous Soil." Vadose Zone
September. doi:10.2136/vzj2011.0118.
Swartjes, Frank. 2011. Dealing with Contaminated Sites. Springer Science & Business
Media.
Warrick, A.W. 2001. Soil Physics Companion. CRC Press.
"Windfinder: Wind Statistics." 2014. Windfinder.com. Accessed March 26. http://www.windfinder.com/windstatistics/boston logan airport.
84

-
85

A.1 Scaling
In order to obtain data from the experiment that is representative of airflow beneath a full- scale building, the appropriate conditions must be replicated in the laboratory. Here, the concept of similitude must be taken into account to scale up the experimental conditions.
Similitude is the theory and art of predicting prototype performance from model observations and is often quantified by various dimensionless numbers (Crowe et al.
2009). Examples of these dimensionless numbers include the Reynolds number, Mach number, and Froude number. For this experiment, the important physical parameters that will be present include the kinetic and viscous forces around the model building caused by the fan. Thus, the Reynolds number is a key criterion for evaluating the correspondence between experimental and full-scale conditions. The Reynolds number is defined as follows:
Where Re is the Reynolds number (dimensionless), V a representative velocity, L is the length of the object, and v is the kinematic viscosity of air.
Ideally, the Reynolds number at full scale and model scale should be equal. However, this is often difficult to achieve. For example, assuming a ten-mile per hour wind against a 25 foot
by 25 foot building, the wind speed required on a one foot by one-foot model in the lab would need to be 250 miles per hour (see Appendix A.1.1). Not only is this infeasible, but additional effects such as air compression would be introduced to the system that would be absent at full scale. According to Crowe et al. (2009), Reynolds number effects often become insignificant at sufficiently high Reynolds numbers or become independent of the
86

Reynolds number. In order to determine the point at which the Reynolds number is sufficiently high or has become independent, the relationship between the pressure coefficient, a dimensionless number that describes the relative pressures throughout a flow field, versus Reynolds number must be examined. According to various wind tunnel experiments for buildings, flow conditions on a model building should be set such that the
Reynolds number is greater than 15,000 to assure Reynolds number independence (Neff et al. 1996). As shown in Appendix A.1.2, in order to keep a Reynolds number greater than
15,000 on the one-foot model building, a wind speed of at least 2.45 feet per second, or approximately 1.7 miles per hour is required.
87

A.1.1 Scaled Wind Speed
To scale wind effects on structures, the Reynolds number is commonly used:
Equation 1
Where Re is the Reynolds number (dimensionless), V is the velocity, L is the length, and v is the kinematic viscosity of air.
In order for the model to simulate realistic conditions, the Reynolds numbers must be approximately equal:
Equation 2
Assuming the kinematic viscosity of air will be the same, a combination of Equation 1 and
Equation 2 reduces to,
Equation 3
For an average wind velocity of ten miles per hour against a 25 foot by 25 foot house, the wind velocity required on the one foot by one foot model is expressed as:
10 25 1
This yields a wind velocity on the model of 250 miles per hour.
88

A.1.2 Minimum Wind Speed
In order to obtain a minimum Reynolds number of 15,000, the minimum velocity on a onefoot by one-foot house can be expressed by:
Equation 4
Inserting the given values for the model building yields:
15,000 1.63 10
-
1
2.45
-
Note the kinematic viscosity value was obtained from Crowe et al. (2009). Therefore, the wind velocity on the model house will need to be greater than 2.45 feet per second.
89

A.2 Porosity
The porosity of the sand used for this study was calculated using the following relationship:
Equation 5
Where 0 is the porosity, Vv is the volume of void space, and VT is the total volume. The void space volume was measured by adding water to a known amount of soil. Once the soil became fully saturated, the volume of water added to the soil was equal to the void volume.
Note that this process assumes the sand does not expand due to the addition of moisture.
For this experiment, 29 mL of water fully saturated 100 mL of soil. This results in a porosity of 0.29.
29
100
0 .29
90

A.3 Sand Hydraulic Conductivity and Permeability
The following section describes the process by which the hydraulic conductivity and intrinsic permeability of the sand was calculated.
The hydraulic conductivity of a soil material can be estimated empirically by use of the
Hazen equation:
Equation 6
Where K is hydraulic conductivity in water in centimeters per second, C is the dimensionless shape factor (varies widely depending on literature), and D
1 0 is the grain diameter at which 10% of the particles by weight are finer. Using a shape factor of 1
(Warrick 2001), and an approximate Dio based on the sieve analysis from Table 1 and
Figure 1, a hydraulic conductivity was calculated as follows:
1.0 0.18 3 .2 10 /
From the hydraulic conductivity test performed in the lab in accordance with ASTM -
D2434 (ASTM Standard D2434), a hydraulic conductivity can be calculated using the following equation:
Equation 7
Where V is the volume of water collected, L is the length of the soil sample, A is the cross sectional area of the soil sample, h is the head difference, and t is the elapsed time to collect
91

the volume of water, V. Multiple measurements were collected over a three-day period in which the test was run. The resulting hydraulic conductivity values are shown in Table 32.
1
2
3
Table 32 Calculated Hydraulic Conductivities
Time of Calculated Hydraulic
Day Conductivity (m/s)
Morning
Afternoon
4.70E-05
5.50E-05
Morning
Afternoon
Morning
1.70E-04
1.65E-04
1.50E-04
The maximum hydraulic conductivity recorded during this test was used as the value for this study. The maximum represents the most accurate value because there was some lag during the first day of the test in which the sand was yet to become fully saturated, resulting in an underestimate. On the third day of the test, a biological film began accumulating on the sand sample, which decreased the flow of water, resulting in an underestimate. Therefore, the maximum value (collected on the second day) represents the most accurate approximation of hydraulic conductivity. The resulting maximum hydraulic conductivity was calculated as follows:
8.6 10
0.002
0.432
0.103
60
1 .7 10
The hydraulic conductivity calculated from the Hazen equation and the constant head test were within a factor of two, suggesting representative values for the porous media used in this study.
To convert this water conductivity to air conductivity, the following relationships were used (Warrick 2001):
92

Equation 8
Where Ka is the air conductivity, k is the intrinsic permeability Pa is the density of air, pa is the dynamic viscosity of air, and g is the acceleration due to gravity. A similar relationship exists for water conductivity:
Equation 9
Where Kw is the water conductivity, pw is the density of water, and [w is the dynamic viscosity of water. Solving for the air conductivity using Equation 8 and Equation 9 yields the following relationship:
Equation 10
Using the calculated water conductivity, the properties of water and air at a temperature of
294 K (Crowe et al. 2009), and one atmosphere of pressure results in an air conductivity as follows:
1 .7 10 -
1.2
-
1._982
997.95 -
9.8210
1.9210
*
* 1.0510
Intrinsic permeability is related to hydraulic conductivity through the following equation
(Warrick 2001):
93

Equation 11
Inserting the values calculated and used above yields the following:
1.0510
-
1.9210
1.2 -
*
9.81 -
1 .7 10
Permeability values for clean sand typically range from 1O-9 to
10-12 m 2 (Warrick 2001).
The permeability calculated for the sand in this experiment is within this range of values.
94

A.4 Percentage of Fully Penetrating Foundation Crack
The percentage of fully penetrating foundation crack is calculated by the area of crack divided by the total foundation area:
% 100
The area occupied by each 3/16" diameter hole drilled into the foundation is calculated using the area of a circle:
3
-
32
0.0276
The building foundation has dimensions of one foot by one foot, resulting in an area of 144 in 2 .
Using all 25 holes drilled in the foundation yields the following foundation crack percentage:
/
25 0.0276
144100
After covering up all but four holes yields the following:
/
4 0.0276
144100
0.5%
0.08%
95

A.5 Differential Pressure Transducer Calibration
In order to convert the output voltage value produced from the pressure transducer, a calibration had to be performed that related output voltage to pressure. To do this, an output voltage reading was recorded for a known pressure. The apparatus shown in Photo
3 was used to create a known pressure value. By forcing air into the tubing, a pressure value resulting from the difference in height of the water column was obtained
(centimeters of water). This value of centimeters of water was then converted to kilopascals (kPa) using the following conversion:
0.09806648
Equation 12
Once this value of centimeters of water was measured, a data point was collected from the output voltage of the pressure transducer, which was connected to the apparatus. The resulting data provides both an input and an output voltage from the transducer for the pressure corresponding to the water column height. The ratio of output volts/input volts was then plotted with the kPa values for each height of water column, as shown in Figure
25.
96

8
.M
6
4
12 in
2
0
0
Seriesl
Linear (Series 1)
1 y = 11.198921x-
R
2
=
0.332572
0.999967
0.2 0.4 0.6
Output/Input (volts/volts)
0.8
Figure 25 Pressure Transducer 1 Calibration
From the equation of the linear fit line to the data, the input and output volts can be converted to Pascals for each transducer using the following equation:
11.198921
0.332572
Equation 13
Where 11.198921 and -0.332572 are constants derived from the line of best fit. Note that the pressure value calculated from the second transducer used in the Depressurization
Experiment included different constants based on a separate calibration analysis. The calibration plot and resulting equation for the second transducer are provided in Figure 26 and Equation 14.
97

4
0 0' 9J
-
-L
~c~es 1 fleJ~ ~Serf~1
,~
11 :9b8?JA U 3$7/1~
0T~1Y4
1 0 04 u' Ok
Output/input (vofts/vokts)
07
Figure 26 Pressure Transducer 2 Calibration
11.195877 0.357714
Equation 14
98

A.6 Frequency Distribution Plot
To determine if the data collected from the Wind Experiment is normally or log-normally distributed, a frequency distribution plot for the data was created. For the data used at each wind speed, the pressure readings were sorted in order from smallest to largest. Each of these values was assigned a rank (1 being the smallest, 2 being the next smallest, etc.).
From this rank, a plotting position was calculated using the following equation:
1
Equation 15
Where n is the number of pressure readings in the data set. The plotting position was then plotted with the following calculated value:
Equation 16
An example of the graph created using untransformed data is provided in Figure 27:
99

a
25 281d
Sta Wad Deviate tue 2!
Figure 27 Untransformed Data Example
The same procedure was followed, except the log of each pressure reading was taken prior to calculating the standard deviate. An example of the graph created using log-transformed data is provided in Figure 28:
4 0 28'2W 4
2 S
Standard Devtate
Figure 28 - Log-Transformed Data Example
For some data sets there is a more significant difference between the two plots, which leads one to choose either an arithmetic or geometric average to properly characterize the data
100

set. In this case, since the two graphs are so similar, there is no significant difference in using an arithmetic or geometric average. One possible reason for the small variability in this analysis is that the range (e.g., 27.1 to 30.2 Pa) of the pressure readings used in the data set is so small.
For this study, the arithmetic average of the pressure data was used. Note that multiple frequency distribution analyses were performed, and each resulted in similar conclusions.
101

A.7 Total Hydraulic Head
Total hydraulic head equation:
2
Equation 17
Where z is the elevation head, referenced to a common datum; is the pressure head, where P is the absolute pressure, p is the density of air, and g is the acceleration due to gravity; and is the velocity head, where V is the air velocity, generally taken as the average linear velocity over a control cross-section.
102

A.7.1 Elevation Head
The elevation head was measured from a common datum, specified in Figure 13, Figure 14,
Figure 21, and Figure 22. Elevation head values range from 0 to 0.27 meters.
103

A.7.2 Absolute Pressure Conversion
To determine the pressure head, differential pressure readings were added to the absolute pressure at each monitoring location. To calculate the absolute pressure at a given elevation, the ideal gas law can be used to relate pressure and elevation for relatively small elevation changes using the following equation (Warrick 2001):
Equation 18
Where the initial pressure, Po, is equal to the pressure, P, at z = zo, where zo is equal to an elevation of 0 meters; M is the molecular weight of air (28.96 g/mol); g is the acceleration due to gravity (981 cm/s 2 ); R is the universal gas constant [8.314x10
7 erg/(mol*K)]; and T is temperature (degrees K). For this study, it was assumed that the initial pressure at zo was atmospheric (101,325 Pa) for each of the experiments. This initial pressure value was just used as a reference point and was intended to allow each test to be compared at an equal starting value. The absolute pressure used in this study represents the initial pressure at a given monitoring location elevation before any wind or vacuum was applied to the apparatus, referenced to a common pressure at zo. An example calculation using an elevation of 26.67 cm, and T of 294 K:
101,325
* 101,324.88
This calculation was performed for each monitoring location elevation and is displayed in
Table 6 through Table 17 and Table 19 through Table 30.
104

A.7.3 Total Pressure
To determine the total pressure at each monitoring location, the absolute pressure was added to the change in gage pressure observed from the impact of the wind or building vacuum. As described in Appendix A.6, the change in gage pressure was calculated by taking the difference of the arithmetic average initial baseline and the arithmetic average pressure readings recorded for each wind speed or building vacuum:
Equation 19
An example calculation using the previously calculated absolute pressure is as follows:
101,324.88 32.59 32.69 101,324.78
Total pressure calculations for each location are available in Table 6 through Table 17 and
Table 19 through Table 30.
105

A.7.4 Pressure Head
Using the pressure head portion of Equation 17, a total pressure head was calculated:
Equation 20
Where p is the density of air and g is the acceleration due to gravity (9.81 m/s 2 ). To account for the fact that air is a compressible fluid and its density changes with elevation, the density of air at each calculated absolute pressure was calculated using the ideal gas law:
Equation 21
Where P is the calculated absolute pressure and R is the universal gas constant (8.314
m
3 *Pa/mol/K). Using the absolute pressure, the air density at this example monitoring location is calculated:
28.96-
8.314
101,324.88
294
Inserting this density into Equation 20 yields:
1000-
101,324.78
1.2-- 9.81--
8,604.30
1.20049-
106

A.7.5 Velocity Head
To calculate velocity head, the velocity of the air was approximated by the following equation (Warrick 2001):
Equation 22
Where
Va is the average linear velocity of the air,
Ja is the volumetric flux density, and
Oa is the saturated air content. The sand used in this study was dry; therefore the saturated air content is equal to the porosity. By using the total pressures, the volumetric flux density for horizontal airflow is described as a simplified form of Darcy's Law:
Equation 23
Where k is the intrinsic permeability (1.7x10-11 M
2
, as calculated in Section Appendix A.3), ta is the dynamic viscosity of air (1.92x10-s kg/m/s at 294 K), and P is the pressure gradient. To estimate the pressure gradient, total pressure values were divided by the distance between two locations at equal elevations for the wind experiment, assuming completely horizontal airflow within the subsurface. Although this assumption may not be entirely accurate, it is a reasonable in order to obtain an order-of-magnitude estimate of velocity head. An example calculation of Ja using Locations 1 and 14 of the slab-on-grade test:
1.7 10
1.9210
,
81.9 Pa
0.36 m' 2 .0
10
107

Inserting this Ja into Equation 22:
2.010
6 .9 10 -
Inserting this velocity into Equation 20 yields the following:
6.910 -
2 9.81-
5 .9 10
Compared to the prior pressure head calculation (8,608.48 m), this value is negligible and is therefore ignored in the total hydraulic head equation. For additional comparison, differences in total head at different locations are generally larger than 10-2 m (see Table 6 through Table 17 and Table 19 through Table 30), further suggesting that velocity head is negligible. Note that the largest pressure gradient was observed in the wind experiment, so a separate calculation for the depressurization experiment was not performed.
Overall, these calculations show that elevation and pressure are the major contributors to total head for this study. These total head values are the values used in the SEEP/W analysis to create the isopotential contours described in Sections 3.1.3 and 3.2.3.
108

A.8 Oxygen Replenishment Rate
In order to calculate the oxygen replenishment rate, the ratio of volume of air/moles of air must be calculated. Assuming ideal gas conditions, this relationship can be calculated from the ideal gas law re-arranged:
Equation 24
Where V is volume of air, n is the number of moles, R is the universal gas constant (0.082
L*atm/K/mol), T is the temperature in Kelvin, and P is pressure. Assuming a temperature of 294 K and a standard pressure of 1 atm yields the following:
0.82 * 294
24.1
1
To convert the flow rate of air to an oxygen flux rate, the following equation was used:
0.21 32
24.1 -
Equation 25
Where Qair is the flow of air through the subsurface beneath the building; 0.21 moles of oxygen/moles of air corresponds to the approximate fraction of oxygen in air under ideal gas conditions; 32 grams/mol of oxygen is the molecular weight of oxygen (02); and 24.1
L/mol is the value calculated using Equation 24. Inserting an example Qair of 3.02 cm 3 /s into Equation 25 yields an oxygen flux rate of approximately 8.42x10
4
g02/ second or 0.05 g02/minute.
109

The total amount of oxygen present beneath the building in the specified target area can be calculated by replacing the flow of air with the volume of air in Equation 24, as shown here:
18,878 0.21
32
5.26
24.1 - 1000
Where 18,878 cm 3 is the volume of air in the target area beneath the building. The oxygen replenishment rate was calculated as follows:
100
Using the example values calculated above yields following value:
0.05 -
5.26
100 0.95
This value is the percent of the total oxygen in the target zone replenished every minute at this example flow rate of air.
110

-
111

B.1 Wind Experiment
B.1.1 BAS
Location 1
40
45
40
20
50 100 150 200 250
Time (seconds)
300 350 400 450 S0
Location 2
30
50 100 150 200 250
Time (seconds)
300 30 400 450 500
112

Location 3
28
26
24
29
50
100 150 200 250
Time (seconds)
300 350 400 450 500
Location 4
24
23
0
50
100 150 2uu
Time (seconds)
113
"o

Location 5
285
27
26
25
2 1
23.5
0 50 100 150 200 250
Time (seconds)
100 350 400 450 500
Location 6
26 .-..
25
24
21
20 p 50 100
150 200 250
Time (seconds)
100 350
400 450 500
114

Location 7
275-
27
26-A
26
25
25
24 5
0 50 100 150 200 250
Time (seconds)
300 350 400 450 500
27.5
27
26.5
26 54
E2fI/
Location 8 lSfs
20ft/s
0.25.5
25
24 5
24
0 50 100
150 200 250
Time (seconds)
300 350 400 450 500
115

Location 9
25.5
25
27.4
27.2
27
268
26.6
214
S26
272
0 50 100
150 200 250
Time (seconds)
300 350 400 450 ,00
Location 10
25.8
50 100 150 200 250
Time (seconds)
300 3SO 400 450 500
116

Location 11
26.4
26
2
26
2
5.8
25.6
&2542
25
26
268
26.2
0
268
26.6
26A
276
274
27.2-
27
--
50 100 150 200 250 lime (seconds)
300 350 400 450 500
Location 12
L0t/EI/
20ft/s
24.6 -7-
24A
24 2
0 50 100
160 200 250
Time (seconds)
300 350 400 450 500
117

28
Location 13
27,5 a.
26,5
29
90 100 1S0 200 250
Time (seconds)
300 3S0 400 4S0 00
Location 14
0 0 100 150 .00 290
Time (seconds)
300
350 400 490 900
118

Location 15
29
28
27
25
24
23
22
21
20
0 50 100 150 200 250
Time (seconds)
300
-
350 400 450 S00
Location 16
29
27
25
23
21
19
17
0 50 100 10 200 250
Time (seconds)
300 350 400 450 500
119

B.1.2 BASSW
50
45
40
30
Location 1
Time (seconds)
Location 2
30
25
50 10r 15i
200 .50
Time (seconds}
300 350 400 450
500
120

Location 3
30
28
L2i
26
S25
.
24
I
25.
2
24.
5
2
7 23.
IL 2 3
22,
21.
2 2
2
0
IL E
A&A
21, f"r
21
20
0
50 100 150 200 250
Time (seconds)
300 350 400 a
I
I
450 500
Location 4
50 100 150 200 250
TIme (seconds)
300 350 400 450 500
121

Location 5
225
215
21
25 5
25
24.5
24
*7 23.5
23
100 150 200 250
Time (seconds)
300 350 400 450
500
Location 6
2 S
25--
24 5
24
235
23
-
0 50 100 150
200 250
Time Iseconds)
300 350 400 450 Soo
122

Location 7
25 5
25
24.S
24
23.5
23
22 5
0
25+5
25
50 100 150 200 250
Time (seconds)
300 350 400 450 500
Location 8
10ff/
20ff/s
24
S23.5
22
0 100 200 300
Time (seconds)
400 500 600
123

Location 9
24.5
24
23,5
23
22.5
0 50 100 150
200 250
Time
(seconds)
300 350 400 450
5300
Location 10
24
I
I
100 150 200 250
Time
(seconds)
300 350 400 450 )00
124

Location 11
25
24.5
265
26
25
24
23.5
0
50 100 150 200 250
Time (seconds)
300 350 400 450 500
Location 12
27,5
27
26.5
26
7 25 5 jr 25
245
23
24
23
0
50
100 150 200 250
Tkne (seconds)
300 350 400 450 500
125

Location 13
27
265
26
25
23.5
7 7
27 S
0
50 100 ISO 200 250
Time (seconds)
300 350 400 450 o5o
Location 14
265
25 --
225
23
0 0 100 150 200 2$SO
Time
(seconds)
300
350 400 450 500
126

Location 15
27
26
25
23
22
21
20
0
27
50
100
150 200 250
Time (seconds)
300 350 400 450 500
Location 16
-
25
23
21
19
17
15
0 50 100 ISO 200 250
Time (seconds)
300 350 400 450 500
127

B.1.3 SOG
Location 1
60
50 c 45
S40
30
20 i 50 100 150 200 250
Time
(seconds)
300 350 400 450
Location 2
-730
241
20
50
100 150
200 "50
Time (seconds)
300
350 400 450 500
128

Location 3
32
30
3 28
26
24
31
0 50 100 150 200 250
Time
(seconds)
300 350 400 450 500
Location 4
28
727
$26
24
23$
22
0
50 100 150 200 250
Time
(seconds)
300 350 400 450 500
129

Location 5
26
2S
24
28
26
50 100 150 200 250
Time Iseconds)
300
350 400 450 500
Location 6
50 100 15r 200 250
Time (seconds)
300 350 400 45U 500
130

10 ff/s
Location 7
5/s2f/
28
271
27
26
255
245
24
0 s0 100 150 200 250
Time (seconds)
300 350 400 450 500
Location 8
21
24.1
26
245
24
0
28
27.5
27
26.1
50 100 ISO
200 250
Time
{seconds)
300 350 400 450 500
131

Location 9
265
24,5
24
25.5
25
27
26 5
100
200 300
Time (seconds)
Location 10
400 500 600
25.5
24
C) 100 200 300 ime (seconds)
400 500 600
132

Location 11
27 5
IL
26
25.5
2S
24.5
100 200 300
Time Isecond5)
400
Location 12
500
600 700
26
25.5
25
24,$
27.5
27
26.5
24
23.5
0 100 200 300
Time (seconds)
400 500 600 700
133

Location 13
26.5
26
25
5
25
24 5
24
23
22 5
0 100 200 300
Time (seconds)
Location 14
400
500
600
21
I I
50 100 150 200 250
Time (seconds)
300 350 400 450 500
134

B.1.4 SOGSW
45
10l/
Location 1
5Wts 20 ft/s
40
35
30
25
20
0 50 100 150 200 250
Time (seconds)
300 350 400 450 500
Location 2
34
32
30
26
24
50
100 150 200 "50
Time (seconds)
300 350 400 450 500
135

Location 3
28 a
27
29
28
24
31
50
100
150 200 250
Time
(seconds)
300 350 400 450 -00
Location 4
25
24
50
100
150 200
250 ime (seconds)
300 350
400 450 OuU
136

28-
Location 5
10fts 15ft/s2oftls
28.5
28
27 5
27
27
26.5
26
25.5
25
24
5
24
0 50 100 150 200 250 inme
(seconds)
300 350 400 450 500
1ft/s
Location 6
[ 5It/I
2Lft/
25.5
245
245
0
50 100 150 200 250
Time
(seconds)
300 350 400 450 500
137

Location 7
27
26
25.5
245
50 100 150
200 250
Time (weods)
300 350 400 450 Soo
Location 8
24
5
24
100 200
Time
(seconds)
138
WO

Location 9
28
27,5
26
25.5
26.5
26
275
27
25
0 50 100 150 200 250
Time (seconds)
300 350 400 450 500
Location 10
25
24
0
100 200 300
Time (seconds)
400 500
600
139

Location 11
2?
27
5
27
S26 5
26--
2 5.5
25
0 100 200 300
Time
(seconds)
1aft/s
Location 12
400
2fs
500 600
24
23 5
25
24
5-
26
5
26
S25.5
275
7
50 100 150
200 250
Time (seconds)
300 350 400 450 500
140

Location 13
28
27
23
21
25
24
23
29
28
27
26
S25
0 50 100 150 200 250 nme (seconds)
300 350 400 450 500
Location 14
500
Time (seconds)
141

B.2 Depressurization Experiment
B.2.1 BAS_0.08%
20
Location 1
10
10
15
20
S
0 20 40 F0 100 140 160 200 220 260 2 0 100 ;20
---
Stbburfav
L72 a
Time (seconds)
Location 2
15
10
10
15
0 20
40 80 100 120
19.4PO
160 IS
220 2-0 280 300 120 340
-BUb(dm
L7.3i
Time (seconds)
142

Location 3
20
10
-10
-15
20
10 is
20
0
0
20 40
80 100
140 160 200 220
50 280 300 320 340
Time (seconds)
Location 4
20
15
10
5
0 20
40
1
10.9L
80 100 140 160 200 220 i 60 280 300 320
-Buildmig
Subsurface rime (seconds)
143

Location 5
10
10
0
20 40
19A PO
80 100 1 0
160
"Jo.e,
200 220 60 280 300 320
-iuIlding
--
StI SbsIrf atCe
Time (seconds)
Location 6
10
10
0 20 40 6 100 114 140 160 00 220
4 26 280 300 320
Sh us dC
27.2 P
Time (seconds)
144

Location 7
20
10
0
0 20 40 80 100 140 160 200 220
10
15
20
Time (seconds)
Location 8
280 100 320
-Buiding
-Subsurface
-10
^NwrWY
10
0 20 40 80 100 140 160 jo 220 260 280 300 320
-Building
-Subsurface
27.2 Pf
Time (seconds)
145

10
Location 9
20
1s
10
0 20 0 80 100
140 160 200 260 280 300 320
Bulldln ,
-50lbsurftan
Time (seconds)
Location 10 vr7.2A"
IS
15
10.9Pa
0 20 40 FA 80 100 140 160
220 26 280 300 320 40 360 380
-suddin,
-substflace
27.2 Pa
Time (seconds)
146

20
IS
10
Location 11
20
15
10
CL
0 20 40
80 100 120 160 18
10
27.2PO
Time (seconds)
Location 12
260 280 300 320
Butding
-Subsurf act:
W-V*NA
10
0
0 20 40 60 100 120
30
180 20C 240 260 300 320 340 360
Time (seconds)
147

Location 13
WN-VAII-l
10
10
1'1
0 20 40 0 100 :0 160 180
220 2 230 300 320 340
27.2fP
Time (seconds)
Location 14
20
10
0
20
40
Eu 100
140 160 180 200 220 2
280 300 320 340
-suldincg
-SUbsuArfaf
Time (seconds)
148

Location 15
20
10
CL
U
0 20 40 so 100
EV14
140 160 200 220 260 280 300 320
-Budding
10 is
Tme (seconds)
Location 16
10
-5
0 20 40
10
80 100
140 160 200 220
260 280 300 320
Time (seconds)
149

10
1
Location 17
20
V-v6wjvf%.d-
10
L~E1
0
0 20 40
80 100 14
160 1 l o0 220
280 300 320 140
-
BoIidfn
Time (seconds)
06j 4
150

B.2.2 BAS_0.5%
40
35
Location 1
25
20
10
5.8PL
10.1 P
0
0 20 40 60 80 100 120 140 160 180 200 220 240 260 280
Time (seconds)
300 320
Location 2
--
-Buildng
Subsurface
~YYVS~Av~~
EkI
10
5
V_*A
E~Fi
0
0
20 40 60 80 100 120 140 160 180
Time (seconds)
200 220 240 260 280 300 320
-
-Building
Subsurface
151

Location 3
20
15
10
-buldng,
-
S
OSU I m k
1 0.1
Pa
25
0 20 40 60 80 100 120 140 160 180 200
Time (seconds)
220 240 260 280 300 320 340
Location 4
20 p.8Po
I."
Sutldin
13
0
20 40 60 80 100 120 140 160 180
Tme (seconds)
200 220 240 260 280 300 320 340
152

Location 5
30
15
10 k
LO. i
-Building
-Subsurface
20
I5
10
0
20 40 60 80 100 120 140 160 180
Time (seconds)
200 220 240 260 280 300 320 340
Location 6
I~E1
-Budding
--
Subsurface
0 20 40 60
80 100 120 140 160 180
Time (seconds)
200 220 240 260 280 300 320 340
153

Location 7
20
10
L~I1
N**%V
SubstIdfm
25
0
0 20 40 60 80 100
120 140 160 180
Time
(seconds)
200 220 240 260 280 300 320
Location 8
15
10 vwY
43AM
1.|
0 20 40 60 80 100 120 140 160
Time (seconds)
180
200 220 240 260 280 300 320
St l)UfJc
154

Location 9
21)
S15
10
L~E1 Buiding
-Subsurf ce
10.1 Pa
13.8
Pa
10
14
12
10
8
20
0 20 40 60 80 100 120 140 160 180 200 220
Time (seconds)
240 260 280 300 320 340 360
Location 10
P
U.
7 1
-
Building
Subsurfact
0
0 20 40 60 80 100 120 140 160
Time (seconds)
180 200 220 240 260 280 300 320
155

Location 11
20
10
0
20 40 60 s0 100 120 140 160 180
Time (seconds)
200 220 240 260 280 300 320 40
Location 12
-1uI)',w
5.8Pa
10
20 40 60 S0 100 120 140 160 180
Time (seconds)
200 220 240 260 2 0
100 120 340
156
-widl.

Location 13
VO^-A~
20
15
10
0 20 40 60 80 100 120 140 160 180
Time (seconds)
200 220 240 260 280 300 320
Location 14
20
eL-E1
10
13.89
0 20 40
60 80 100 120 140 160 180 200 220 240 260
Time (seconds)
280 300 320 40
157
-
Budding
Subsurfacc

Location 15
20
MIV N
I.8 P1
L0.AIE
|Lk1
0
20 40 60 80 100 120 140 160 180
Time (seconds)
200 220 240 260 280 300 320
Location 16
-ulling
20
10
F13.8Pt
0 20 40 60
80 100 120 140 160 180
Time (seconds)
200 220 240 260 280 300 320
340
-Buildinp
-Subsurfac,
158

lb
~AAANV
L414
16
Location 17
(A
I01P
0 20 40 60 80 100 120 140 160
Time (seconds)
180 200 220 240 260 280 300 320
159

B.2.3 SOG_0.08%
Location 1
20
10
10
0 20 40 60
20
0 120 160 180 220 240 280 300 320 340
___subsa
Time (seconds)
Location 2
10
CL
10
20 40 80 I0u 140 160 W 220 260
280 i00 320
-br_
20
Time
(seconds)
160

Location 3
30
10
10
0
0 20 40
20
80 100
140 160
LF,6i1
49.4
Fin
220 260 280 300 320 340
-Building
-Subsurface
40
Time (seconds)
Location 4
20
10
CL
0
0 20 40
10
80 100 40 160 18 220 24 280 300 320 340 360 ---
Building
Subsurface
20
30
49.4
Pa
Time (secor
161

Location 5
10 o 20
40
10
80 100 140 160 200 220 260 280
-
300
320 -ShM
Bulding
4l
20
Time (seconds)
Location 6
10
0
.
0
20 40
10 o 100 140 160 1,i
49.4PO
280 300 320 340
-
--u1Idnp
SubsurO,
40
Time
(seconds)
162

20
30
Location 7
30
20
10
10
0
20
40
80 100 140 160
L4.6
P
10 220 260 280 300
Building
320 -Subsrfacc
Time (seconds)
Location 8
49.4 Pa
-20
30
20
10
-10
0 20 40 80 100 10 160
34.6
200 220 260 280 300 320 340 -
Building
Subsurfac
Time (seconds)
49.4P
163

Location 9
30
20
10
CL
10
0 20 40
20
80 100 140 160 200 220 260 280 300 320 340
Time (seconds)
Location 10
30
20
10
10
0 20 40
80 100 140 160
200 220 260 280 300 320 -
K
20
Time (seconds)
164

Location 11
A
..... 01011111
20
10
0
.
0 20 40
10
20
80 100 140 160 200 220 260 280 300 320
-Building
-subsurtatt
49.4
PA
Time (seconds)
Location 12
20
10
0
10
20 40
20
30
18.$Pa
100
W
40 160 200 220 i0 280 300 320
-Busding
-subsuracw
Time (seconds)
165

Location 13
10
20
0 0
20 40
10
20
80 100 140 160
34.-P1
200 220 260 280 300 320
Sukb1)ski fla
40
Time (seconds)
Location 14
20
10
10
0 20 40 80 100
20
S220 240
Time (seconds)
49.4 Pa
280
300 320 340
-Buildng
_
166

Location 15
30
20
10
10
0
0 20 40 a.s5Pa
10 100 140 1>0
34.6iP
200
22 jt,
260 280 00 300 320 340
Building
Time (seconds)
Location 16
20
10
CL
10
0 20 40
20
80 100 140 160
E4.-PE1
0 220 260 280
300 320
--
Building
-subsurfacte
49.4
PO
Time (seconds)
167

Location 17
10 a.
10
0 20 40
10
20
18. 5 PO
80 100 140 160 200 220 260 280 100 320
.
Time (seconds)
168

B.2.4 SOG_0.5%
25
20 is
10
.S Pa
Location 1
~AM~
-Bualding
30
0
20 40 60 80 100 120 140 160 180
Time Iseconds)
200 220 240 260 230 300 320 340
Location 2
20
10
L~i
E~i
0
20 40 60 s0 100 120 140 160 180
Time (seconds)
200 220 240 260 280 300 320
-
-Blding
Subsurface
169

Location 3 rVW~
E2KI
L~~4~Wi
14.8 Pa
10
0 20 40 60 80 100 120 140 160
Time (seconds)
180 200 220 240 260 280 300
320
Location 4
-Suburfcig
10
0 20 40 60 s0 100 120 140 160
Time
(seconds)
180 200 220 240 260 280 300 120
170
-
-Buddinfir
SUturfAOcV

20
1IL
10
Location 5
20
XWAr~
15
10 i.5 i1
14. O I
L~i
30
0
20 40 60 80 100 120 140 160 180
Time (seconds)
200 220 240 260 280 300 320
Location 6
-
-Buiding
Subsurface
Al"E
--
---
Buildng
Subsurfice
0
20 40 60 80 100 120 140 160
Time (seconds)
180 200
220 240 260 280 300 320
171

Location 7
10
10
--
8kidinlfg
-skibsudiace
0 20 40 60 80 100 120 140 160 180
Time (seconds)
200 220 240 260 280 300 320
Location 8
20
15
10
0 20 40 60 80 100 120 140 160
180 200
Time (seconds)
220 240 260 280
300 120
---
B0,m
172

30
Location 9
1
Nr*
20
-
-Building
SubSurdfcC
10
L~II
20
15
10
30
0 20 40 60 80 100 120 140 160
Time (seconds)
180 200 220 240 260 280 300 320
Location 10
25
L~E1
-
Budding
Subsurface
0
20 40 60 80 100 120 140 160 180 200 220 240 260 280 300 320
Time (seconds)
173

Location 11
30
ANOA&dnAP-
4110
LF~I1
10
10
0
20 40 60 80 100 120
140 160 180
Time Iseconds)
200 220 240 260 280 300 320
Location 12
~MA'
L~I1
^AW
0 20 40 60 80 100 120 140 161
Time (seconds)
180 200 220 240 260 280 300
320
174

Location 13
20
L.AAPN
10
30
V".P^
0
20 40 60 80 100 120 140 160 180
Time (seconds)
200 220 240 260 280 300 320
Location 14 subuding
-subsurface
20
12~I1
10
20.6 Pa
0
0 20 40 60 80 100 120 140 160
Time (seconds)
180 200 220 240 260 280 300 320
Busdng
-Subsurface
175

Location 15
10
10
EI~i~ kdA.VIPN
C 20 40 60
80 100 120 140 160 180
200 220 240 260 280 300 320 340 ime (seconds)
Location 16
--
Bwldmng
20
L~E1
10
W4ArPr
U 20 40
60
80 100 120 140 160
Time (seconds)
180 200 220 240 2601 2s0 100 120
176

Location 17
20
I5
10
U
20 40 60
80 100 120 140 160 180 200 220 240 260 280 300 320
Time
{seconds)
-
-Bulding
Subsurface
177

-
178

C.1 Wind Experiment
C.1.1 BAS
C.1.1.1 10 ft/s
C.1.1.2 15 ft/s
179

C.1.1.3 20 ft/s
180

C.1.2 BASSW
C.1.2.1 10 ft/s
C.1.2.2 15 ft/s
181

C.1.2.3 20 ft/s
182

C.1.3 SOG
C.1.3.1 10 ft/s
I I
C.1.3.2 15 ft/s
183

C.1.3.3 20 ft/s
184

C.1.4 SOGSW
C.1.4.1 10 ft/s
I
I
C.1.4.2 15 ft/s
I
I
185

C.1.4.3 20 ft/s
L....
186

C.2 Depressurization Experiment
C.2.1 BAS_0.5%
C.2.1.1 17.4 cm 3 /s
C.2.1.2 27.9 cm 3 /s
187

C.2.1.3 37.3 cm 3 /s
188

C.2.2 BAS_0.08%
C.2.2.1 17.4 cm 3 /s
C.2.2.2 27.9 cm 3 /s
189

C.2.2.3 37.3 cm 3 /s
190

C.2.3 SOG_0.5%
C.2.3.1 17.4 cm
3
/s
I
C.2.3.2 27.9 cm 3 /s
191

C.2.3.3 37.3 cm 3 /s
192

C.2.4 SOG_0.08%
C.2.4.1 17.4 cm 3 /s
I I
C.2.4.2 27.9 cm 3 /s
193

C.2.4.3 37.3 cm 3 /s
194

-
195

Photo #1 of
16
Description:
RO-TAP mechanical sieve machine used in grain size analysis
Photo #2 of 16
Description: Porosity laboratory test. 100 mL of 100% saturated soil on the left, the remaining
71 mL of the initial 100 mL of water on the right
196

Photo #3 of 16
Description: Constant head hydraulic conductivity laboratory setup
Photo #4 of 16
Description: Data acquisition system. The blue box is the data acquisition module. The module is placed on top of the power source to the module. The box to the right of the computer monitor is a separate device to display the current input voltage
197

Photo #5 of 16
Description:
Screenshot of Acqlipse
Data Acquisition software interface for data acquisition system
Photo #6 of 16
Description:
Differential Pressure
Transducer calibration apparatus
Description:
Depressurization
Experiment Peristaltic pump setup
198

Photo #7 of 16
Description:
Depressurization
Experiment Peristaltic pump setup
Photo #8 of 16
Description: Wind
Experiment Setup including Dayton propeller fan and data acquisition system
199

Photo #9 of 16
Description: Wind
Experiment Basement configuration
Photo #10 of 16
Description: Wind
Experiment Slab-On-
Grade configuration
200

Photo #11 of 16
Description: Wind
Experiment Slab-On-
Grade configuration with sidewalk
Photo #12 of 16
Description: Wind
Experiment Basement configuration with sidewalk
201

Photo #13 of 16
Description:
Depressurization
Experiment 0.5% foundation crack configuration
Photo #14 of 16
Description:
Depressurization
Experiment 0.07% foundation crack configuration
202

Photo #15 of 16
Description:
Depressurization
Experiment Basement configuration
Photo #16 of 16
Description:
Depressurization
Experiment Slab-On-
Grade configuration
203

-
Available on file
-
Available on file
Available on file
204