oEPA
United States
Environmental Protection
Agency
Temporal Variation of VOCs
in Soils from Groundwater
to the Surface/Subs lab
APM 349
RESEARCH AND DEVELOPMENT
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EPA/600/R-10/118
October 20010
www.epa.gov
Temporal Variaiton of VOCs
in Soils from Groundwater
to the Surf ace/Subs lab
APM 349
EPA Contract No. EP-C-05-061
Task Order No.85
Prepared for
Tetra Tech EM Inc.
1230 Columbia Street
Suite 1000
San Diego, CA92101
Prepared for
Dr. Brian A. Schumacher, Task Order Project Officer
U.S. Environmental Protection Agency
Office of Research and Development
National Exposure Research Laboratory
Characterization and Monitoring Branch
Las Vegas, NV89119
Although this work was reviewed by EPA and approved for publication, it may not necessarily reflect official
Agency policy. Mention of trade names and commercial products does not constitute endorsement or
recommendation for use.
U.S. Environmental Protection Agency
Office of Research and Development
Washington, DC 20460
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FOREWORD
The U.S. Environmental Protection Agency (EPA) is charged by Congress with protecting the nation's
natural resources. Under the mandate of national environmental laws, the EPA strives to formulate and
implement actions leading to a compatible balance between human activities and the ability of natural
systems to support and nurture life. To meet this mandate, the EPA's Office of Research and
Development (ORD) provides data and scientific support that can be used to solve environmental
problems, build the scientific knowledge base needed to manage ecological resources wisely,
understand how pollutants affect public health, and prevent or reduce environmental risks.
The National Exposure Research Laboratory (NERL) is the Agency's center for investigation of technical
and management approaches for identifying and quantifying exposures to human health and the
environment. Goals of the laboratory's research program are to (1) develop and evaluate methods and
technologies for characterizing and monitoring air, soil, and water; (2) support regulatory and policy
decisions; and (3) provide the scientific support needed to ensure effective implementation of
environmental regulations and strategies.
This report presents the activities, results, findings, and recommendations associated with monitoring the
variations in active soil vapor sample results near and under a slab over a one-year period. The
experimental program was conducted adjacent to Building 170 at Naval Air Station Lemoore (NAS)
Installation Restoration Program (IRP) Site 14 from November 2008 through October 2009. The work
described in this report is the follow up investigation to Vertical Distribution of VOCs in Soils from
Groundwater to the Surface/Subslab (EPA 2009). This report was co-authored by Mr. James Elliot and
Dr. Greg Swanson of Tetra Tech and Dr. Blayne Hartman of H&P Mobile Geochemistry. The authors
acknowledge the tremendous support of Mr. Frank Nielson and Mr. Mike Quesada, the Navy personnel in
charge of NAS Lemoore environmental operations, who facilitated access to IRP Site 14 to conduct the
testing and provided logistical support and ongoing assistance with operations during the field sampling
activities. The authors also acknowledge the effective field support and technical oversight provided by
the EPA task order project officers, Dr. Brian Schumacher and Mr. John Zimmerman.
NOTICE
The information in this document has been funded wholly by the United States Environmental Protection
Agency under contract #EP-C-05-061 to Tetra Tech EM, Inc. It has been subjected to the Agency's peer
and administrative review and has been approved for publication as an EPA document. Mention of trade
names or commercial products does not constitute endorsement or recommendation by EPA for use.
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EXECUTIVE SUMMARY
Tetra Tech EM, Inc. (Tetra Tech EMI) was contracted by the U.S. Environmental Protection Agency
(EPA) to assess the temporal variation of volatile organic compounds (VOCs) in soils from groundwater
to the surface/subslab over a one-year period and to develop a database of paired macro-purge and micro-
purge soil gas sample measurements. In addition, a study was conducted to assess the effect of purging
parameters (purge rate, purge volume, sample volume) on measured VOC concentrations in soil vapor
samples.
The field study was conducted at Installation Restoration Program (IRP) Site 14 on Naval Air Station
(NAS) Lemoore, California. IRP Site 14 is located in the operations area of NAS Lemoore and consists
of maintenance buildings, hangars, and aircraft parking areas. Chlorinated VOCs are the primary
contaminants that have been found in soil, soil gas, and groundwater at IRP Site 14 near the Building 180
hangar, the adjacent aircraft parking area, and Building 170, where this investigation was conducted. The
plume of chlorinated VOCs at IRP Site 14 is composed primarily of trichloroethene (TCE) and 1,1-
dichloroethene (DCE), with minor amounts of 1,2-DCE, 1,1-dichloroethane (DCA), 1,2-DCA, and
tetrachloroethene (PCE). Two discernable VOC plumes are present at IRP Site 14: one emanating from
the Building 180 area, and one located south and east of Building 170. Two sets of six macro-purge
(standard 1/8 inch tubing size) soil gas monitoring wells were installed along two lines (transects) during
a previous EPA-sponsored investigation at the site. The transects were oriented approximately east-west,
with a southern (primary) transect and a northern (secondary) transect. The southern transect was later
augmented by the installation of three additional vapor sampling locations and the construction of
groundwater monitoring wells at eight locations. Because the historical releases of chlorinated VOCs at
IRP Site 14 were from known point sources, and the transects were not proximate to any of these sources,
the measured soil vapor concentrations within these transects can be considered as deriving from a
groundwater source.
For this study, only the southern transect was sampled. The eastern most soil gas monitoring well was
excluded from the study due to consistent non-detect (ND) results. Thus, for this study, four soil gas
monitoring wells were located on an approximately 6-inch thick concrete slab, and the remaining four
wells were east of the slab, where the ground surface is not covered. At each soil gas monitoring well,
soil vapor probes were installed at 2, 4, 7, and 10 feet below ground surface (bgs). At the four well
locations on the concrete slab, a soil vapor probe was also located immediately beneath the concrete (a
"sub-slab" probe). Collocated micro-purge (0.01-inch tubing size) sampling locations were also installed
along the transect.
The macro-purge and micro-purge vapor probes and the groundwater monitoring wells were sampled on a
monthly basis from November 2008 through October 2009. Soil vapor samples were analyzed on-site in
a mobile laboratory using EPA SW-846 Method 8021. Groundwater samples were analyzed off-site at a
fixed laboratory using EPA SW-846 Method 8260B.
The results of this study demonstrate that at this site, the near-slab environment is in a steady state, or
dynamic equilibrium, governed by diffusive mass transfer. Beneath the slab, vapor- and aqueous-phase
VOC concentrations were approximately in equilibrium and the rate-limiting step governing mass transfer
was the movement of vapors laterally out from under the slab. In the uncovered area, the rate-limiting
step was the transfer of VOCs from deep groundwater up and across the groundwater/soil gas interface;
once in the vapor phase, the VOCs diffused relatively quickly upward and escaped through the uncovered
ground surface. Because the rate of diffusive mass transfer is much slower in the aqueous phase than in
the vapor phase, this process appears to have led to depletion of VOCs in the shallow groundwater
beneath the uncovered area while groundwater concentrations beneath the slab remained quite elevated.
-------
Monthly sampling indicated that groundwater concentrations were relatively stable over the course of the
12-month study period. Vapor concentrations under the slab generally varied by less than a factor of 4,
while the variability in vapor concentrations in the uncovered area was much higher. The variability in
vapor concentrations was not strongly linked to changes in groundwater concentrations, suggesting that
other factors had a greater effect on vapor concentrations.
The paired micro-purge and macro-purge soil gas samples were not well correlated. Statistical analyses
indicated an overall coefficient of determination (r2) based on a linear regression of less than 0.5.
Examination of the depth-specific subdivisions of the data indicated that the correlation between macro-
purge and micro-purge vapor samples decreased with depth. It is suspected that the poor correlation was
due in large part to challenges in collecting representative samples using the micro-purge technique;
specifically, the resistance to gas flow through the 0.01-inch diameter micro-purge tubing results in a
vacuum in the sampling train that may draw in ambient air.
The results of the sampling parameters study are presented in Appendix B of this report and indicate that
purge rate, purge volume, and sample volume had no significant effect on measured VOC concentrations
in soil vapor samples. Vadose zone soils at the NAS Lemoore study site comprise relatively low
permeability silts and clays, and the results of the purging parameter study are consistent with the results
of a similar study conducted at Vandenberg Air Force Base at a site underlain by homogenous, highly
permeable dune sands.
111
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CONTENTS
Section Page
FOREWORD i
EXECUTIVE SUMMARY ii
LIST OF ACRONYMS AND ABBREVIATIONS vi
1.0 INTRODUCTION 1-1
2.0 SITE BACKGROUND AND PROBE LAYOUT 2-1
2.1 IRPSITE 14 SETTING AND BACKGROUND 2-1
2.1.1 Geology and Hydrogeology 2-1
2.1.2 Chlorinated Solvent Plume Conditions 2-7
2.1.3 Selection of IRP Site 14 2-7
2.2 SOIL VAPOR PROBE TRANSECTS 2-7
2.2.1 Macro-Purge Vapor Probes 2-7
2.2.2 Micro-Purge Vapor Probes 2-9
2.2.3 Groundwater Monitoring Wells 2-9
2.3 EXPERIMENTAL DESIGN 2-10
3.0 EQUIPMENT AND METHODS 3-1
3.1 SAMPLE COLLECTION 3-1
3.1.1 Soil Samples 3-1
3.1.2 Soil Vapor Samples 3-1
3.1.3 Groundwater Samples 3-1
3.2 MOBILE LABORATORY 3-2
3.2.1 Analytical Method 3-2
3.2.2 Equipment 3-3
3.2.3 Detection Limits 3-3
3.3 QUALITY ASSURANCE/QUALITY CONTROL 3-3
3.3.1 Field Quality Control Protocols 3-3
3.3.2 Mobile Laboratory Quality Control Protocols 3-6
3.3.3 Project QAPP Deviations and Additions 3-7
4.0 RESULTS AND DISCUSSION 4-1
4.1 DATA SUMMARY 4-1
4.1.1 Soil Sample Results 4-1
4.1.2 Groundwater Sample Results 4-1
4.1.3 Soil Gas Samples 4-4
4.2 DISCUSSION 4-13
4.2.1 Distribution of VOCs in the Subsurface 4-13
4.2.2 Temporal Variability 4-15
4.2.3 Macro-Purge versus Micro-Purge Sampling 4-17
4.2.4 Sampling Parameters Study 4-22
5.0 CONCLUSIONS 5-1
6.0 RECOMMENDATIONS 6-1
7.0 REFERENCES 7-1
IV
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CONTENTS (Continued)
Page
APPENDICES
A Sampling Trip Report
B Purging Parameters Study
C Example Chromatograms and Laboratory Data
D Groundwater Sample Data
E Soil Vapor Sample Data
F Soil Vapor Profiles
G Statistical Analyses
2-1 Detailed Site Map, IRP Site 14, NAS Lemoore, California 2-2
2-2 Groundwater Contours, A Zone, January 2007 2-4
2-3 Trichloroethene Plume in the A Zone, April 2009 2-6
2-4 Soil Vapor Probe Transects and April 2009 Groundwater TCE Concentrations 2-8
2-5 Soil vapor Probe Construction Schematic 2-11
4-1 South Transect Detail 4-3
4-2 Groundwater TCE Concentrations 4-5
4-3 Groundwater Levels 4-6
4-4 Macro-Purge Vapor Probe TCE Concentrations 4-12
4-5 Micro-Purge Vapor Probe TCE Concentrations 4-12
4-6 Schematic Isoconcentration Contours (January 2009 macro-purge data) 4-14
4-7 Temporal Trends in Soil Vapor Concentrations Under the Slab 4-16
4-8 Temporal Trends in Soil Vapor Concentrations in Uncovered Locations 4-16
4-9 Schematic Isoconcentration Contours (June 2009 macro-purge data) 4-18
4-10 Plot of Micro-Purge versus Macro-Purge TCE Concentrations 4-19
4-11 Plots of Micro-Purge versus Macro-Purge TCE Concentrations by Depth 4-20
4-12 Linear Plot of Purge Rate Experiment Data 4-23
4-13 Linear Plot of Purge Volume Experiment Data 4-24
4-14 Linear Plot of Sample Volume Experiment Data 4-24
Tables
2-1 Typical Physical Properties of the A Clay 2-3
2-2 Typical Physical Properties of the Vadose Zone and A-zone Aquifer 2-5
2-3 Macro-Purge Soil Gas Probe Installation Details 2-10
3-1 Summary of Monthly Sampling Rounds 3-2
3-2 Summary of Soil Gas and Groundwater TCE Duplicate Results 3-4
4-1 Summary of TCE Concentrations in Soil ((ig/kg) 4-1
4-2 Summary of TCE Concentrations in Groundwater ((ig/L) 4-2
4-3 Decrease in TCE Concentration per Foot (percent/distance) 4-2
4-4 Summary of Groundwater Level Measurements (feetbTOC) 4-5
4-5 Summary of TCE and PCE Concentrations in Macro-Purge Vapor Samples, January 2009 4-6
4-6 Summary of TCE and PCE Concentrations in Micro-Purge Vapor Samples January 2009 4-7
4-7 Comparison of TCE Concentrations in Macro-Purge and Micro-Purge Vapor Samples 4-8
4-8 Statistical Parameters for Regression Curve Y = a + bX 4-19
4-9 Statistical Parameters for Regression Curve Y = bX 4-21
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LIST OF ACRONYMS AND ABBREVIATIONS
AETL
bgs
Cal/EPA
°C
DCA
DCE
DFA
DTSC
BCD
EPA
GC/MS
HPMG
ID
IRP
LCS
(ig/m3
Mg/L
mg/L
mL
mL/min
NAS
ND
NERL
ORD
PCE
PID
ppbV
PVC
QA
QAPP
RPD
Tetra Tech EMI
TCE
TO
UST
VOC
American Environmental Testing Laboratory
Below ground surface
California Environmental Protection Agency
Degrees centigrade
Dichloroethane
Dichloroethene
1,1-difluoroethane
Department of Toxic Substances Control
Electron capture detector
U.S. Environmental Protection Agency
Gas chromatograph/mass spectrometry
H&P Mobile Geochemistry
Internal diameter
Installation Restoration Program
Laboratory control sample
Micrograms per cubic meter
Micrograms per liter
Milligrams per liter
Milliliter
Milliliters per minute
Naval Air Station
Non-detect
National Exposure Research Laboratory
Office of Research and Development
Tetrachloroethene
Photoionization detector
Part per billion by volume
Polyvinyl chloride
Quality Assurance
Quality assurance project plan
Relative percent difference
Tetra Tech, EM Incorporated
Trichloroethene
Task Order
Underground storage tank
Volatile organic compound
VI
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1.0 INTRODUCTION
Soil vapor data are widely used in site investigation and remediation projects to delineate volatile organic
compound (VOC) vapor plumes, as a screening tool to refine soil and groundwater sampling efforts, to
track the progress of soil remediation, and to assess the vapor intrusion pathway. Vapor intrusion is of
particular concern, as it can be the primary grounds for remediation at VOC sites. A critical issue in
assessing the vapor intrusion pathway is understanding the distribution and migration of VOCs from the
subsurface source to the near surface environment.
It is commonly held that VOCs in a groundwater plume will migrate from groundwater through the
vadose zone and either disperse to the atmosphere if the surface is uncovered, or potentially migrate into
the indoor air of an overlying structure (i.e. vapor intrusion). Numerical models have been developed to
describe the migration of VOCs in the subsurface environment and to assess the effects of a building
foundation or slab (Abreu and Johnson 2005); however, these models incorporate a variety of simplifying
assumptions. Overall, few data are available to document the behavior and distribution of VOC vapors
through the soil column from groundwater to the surface/subslab environment and the variability in that
distribution over time.
Variation in sampling methods, field conditions, and analytical methods may result in variability in soil
vapor measurements. These sources of variation are essentially "noise" in the data, making it difficult to
reach a clear understanding of the migration of VOCs in soils. A critical element in obtaining usable soil
vapor data is the collection of representative samples. A variety of sample collection techniques are
commonly used in the industry, but little data exist to evaluate the relative merits of the different methods.
The two primary objectives of this investigation were to: (1) measure the distribution of VOCs in the
vadose zone and shallow groundwater in order to improve our understanding of the mechanisms of vapor
migration and intrusion and (2) monitor the distribution of VOCs over the course of a year to assess the
temporal variability. Secondary objectives included comparison of sampling results obtained from
industry standard vapor probe implants (referred to here as "macro-purge" probes) and a new "micro-
purge" methodology, and assessment of the effect of sampling parameters (i.e., purge rate, purge volume,
and sample volume) on measured soil vapor concentrations.
1-1
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2.0 SITE BACKGROUND AND PROBE LAYOUT
The field sampling and analysis portion of this project was conducted at Installation Restoration Program
(IRP) Site 14, on Naval Air Station (NAS) Lemoore. NAS Lemoore is located in the California Central
Valley, approximately 40 miles south of Fresno and 180 miles northwest of Los Angeles (Figure 2-1).
2.1 IRPSITE 14SETTING AND BACKGROUND
Site 14 is located in the operations area of NAS Lemoore and consists of maintenance buildings, hangars,
and aircraft parking areas (Figure 2-1). Chlorinated VOCs are the primary contaminants that have been
found in soil, soil vapor, and groundwater at IRP Site 14 near the Building 180 hangar, the adjacent
aircraft parking area, and near Buildings 188 and 170. The plume of chlorinated VOCs at IRP Site 14 is
composed primarily of trichloroethene (TCE) and 1,1-dichloroethene (DCE), with minor amounts of 1,2-
DCE, 1,1-dichloroethane (DCA), 1,2-DCA, and tetrachloroethene (PCE). Fuel residuals are also
commingled with the chlorinated solvents; specific VOCs associated with the fuel residuals include trace
amounts of benzene, toluene, ethylbenzene, and xylenes. Other VOCs detected at IRP Site 14 include
chloroform and trichlorotrifluoroethane (Freon-113). Two coalesced VOC plumes are present at IRP Site
14: one emanating from the Building 180 area, and one located south of Building 170 (Figure 2-1).
There are several suspected source areas including industrial wastewater lines, storm drains, a manhole, a
wash rack, and six former underground storage tanks (USTs). There are also possible spills or releases to
uncovered areas or aircraft parking areas as a result of various practices associated with aircraft
maintenance. All industrial waste water lines have been repaired or replaced, and all USTs at IRP Site 14
have been removed. Thus, soil gas VOC concentrations at the site are driven by groundwater
concentrations in all locations except immediately adjacent to historical point release points.
2.1.1 Geology and Hydrogeology
2.1.1.1 Regional Geologic Setting
NAS Lemoore is located in the San Joaquin Valley, the southern half of California's Central Valley, a
400-mile-long structural basin that borders the Sierra Nevada Mountain Range. The Central Valley is
underlain by a large fault block that tilted down toward the west as the basement rock rose to the east to
form the Sierra Nevada.
The valley has continuously subsided throughout the Pleistocene and Holocene periods. Subsidence
steepened the gradients of rivers that emerge from the Sierra Nevada, promoting the development of
alluvial fan deposits and their subsequent preservation. The fans themselves consist largely of coarse-
grained channel deposits, as finer-grained sediments are discharged by floodwaters that spill out onto the
plain beyond the toe of the fan. A similar process was active on the slopes of the Coast Ranges that
borders the valley to the west.
NAS Lemoore is located immediately west of the trough of the valley. The trough is the lowest and most
level portion of the valley. The ground surface elevation at NAS Lemoore is approximately 230 feet
above mean sea level. Lakes and playas have occupied the trough repeatedly throughout Quaternary
time, leaving behind lacustrine deposits. Lacustrine deposits at NAS Lemoore primarily consist of clay.
The three most extensive lacustrine clays have all been mapped beneath NAS Lemoore; they are referred
to as A Clay, C Clay, and E Clay. The A Clay underlies NAS Lemoore at a depth of approximately 50
feet below ground surface (bgs).
2-1
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UNPAVED AREA
FORMER UNPAVED AREA
LANDSCAPED AREA
TCE PLUME A ZONE- JANUARY 2007
INDUSTRIAL WASTEWATER LINE
STORM DRAIN
OPERATIONS
AREA
,
Lemoore
MAS
FORMER STORM DRAIN
NAS LEMOORE BOUNDAR
ADMINISTRATION
AREA
5000 0 5000 10000
III I
SCALE: 1" = 10000'
AIRCRAFT PARKING
STUDY AREA
WASH
RACK
50' 0 50' 100
' <-
SCALE: 1" = 100'
NAS Lemoore-Sitel 4
U.S. Navy, NAVFAC Southwest, San Diego, California
HGURE2-1
DETAILHD9TEMAP
STREMVIST085
JET ENGINE TEST
CELLS AND
USTs 173 AND 174
WASH
RACK
(Tt| Tetra Tech EM Inc
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NAS Lemoore is also located near the outer edge of the Kings River alluvial fan. As a result, alluvial
deposits interfmger with lacustrine clays beneath NAS Lemoore. Alluvial deposits are typically olive
brown to olive gray in color and contain sporadic cemented horizons. In contrast to lacustrine deposits,
alluvium is heterogeneous and contains stringers and lens-shaped sand channel deposits that grade
laterally to silty floodplain deposits.
Sediments at IRP Site 14 have the characteristics of both alluvial and lacustrine environments, indicating
pulses of alluvial deposition into a closed, possibly ephemeral lacustrine environment. Lacustrine
environments generally dominate in periods of cooler, wetter climates, such as during periods of
glaciation, the last of which occurred about the time the A Clay was deposited.
2.1.1.2 IRP Site 14 Geology and Hydrogeology
Geologic deposits beneath IRP Site 14 consist of an alluvial aquifer composed of sand, silty sand, and
sandy silt interfmgered with less permeable deposits of clayey silt and silty clay. The alluvial assemblage
is interrupted by clay interbeds of lacustrine origin at various intervals.
Several groundwater zones are identified beneath IRP Site 14. The uppermost (shallow) groundwater
body is designated as the A aquifer zone. The A-Clay underlies the A-zone at a depth of approximately
45 to 50 feet, forming a semi-impermeable barrier that the A-zone groundwater is perched on. The depth
to A-zone groundwater ranges from 10 to 14 feet bgs. The predominant site-wide groundwater flow in
the A-zone is to the east/northeast, with a gradient on the order of 0.004 (Figure 2-2).
The A-Clay appears to be laterally continuous across the site between depths of 45 and 50 feet (-35 feet
below the groundwater table). Several cores through the A-Clay have been obtained for the IRP
investigation at Site 14 and it is typically logged as a stiff clay with low plasticity but does not appear
reduced. Geotechnical samples collected in this interval exhibited a relatively high fraction of organic
carbon (foc) of between 1 and 2 percent (Table 2-1).
Table 2-1
Typical Physical Properties of the A Clay
PARAMETER
Clay (%)
Dry Bulk Density (lbs/ft3)
Bulk Density (lbs/ft3)
Moisture Content (%)
Fraction Organic Carbon (%)
Percent Gravel (%)
Percent Sand (%)
Percent Silt Or Percent Clay (%)
Porosity, Effective
Porosity, Total
USCS Classification (field)
Geotechnical Analysis Classification
RESULT
21.72
96.77
123.81
27.94
1.40
0.00
9.15
90.85
0.03
0.40
clayey silt
lean clay
2-3
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LEGEND
so so STORM DRAIN AND LATERALS
DECK DRAIN
AIRCRAFT SERVICE CONDUIT
WELLS SAMPLED IN JANUARY 2007
GROUNDWATER ELEVATION
ESTIMATED GROUNDWATER FLOW
DIRECTION
AND HYDRAULIC GRADIENT
WELL DEPTH ZONE DESIGNATIONS
(SCREENED INTERVAL)
A = 0-45 FEET BGS
B = 45-60 FEET BGS
C = 60-75 FEET BGS
D = 75-95 FEET BGS
E = > 95 FEET BGS
NOTE:
HYDRAULIC GRADIENT OF
LESS THAN 0.001 ARE
INDICATED BY A DASHED
ARROW
MW14-09A
216.95
MW14-64
(A.D)
MW14-251A
216.93
MW14-251A
216.93
MW14-68A
217.34
MW14-
MW14-
MW14-51A
217.59
AIRQRAFT PARKING
MW14-70A
V215.51
Mf14-259B$
MW14-69A
^217.39
MW14-05A
218.09
188-1-MW2
217.93
MW14-03A
217.08
ORMER
T 188-
MW14-43A
217.98
MW14-54A
217.80
50' 0 50'
n rl h
SCALE: 1" = 100'
100'
NASLemoore-Site14
U.S. Navy, NAVFAC Southwest, San Diego, California
FIGURE 2-2
GROUNDWATER CONTOURS - A ZONE
JANUARY 2007
STREAMS TO 85
Tetra Tech EM Inc.
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Alluvium in the A-zone (~12 to 45 feet bgs) consists largely of granular alluvium (predominantly sands),
especially in the vicinity of the apparent TCE source locations. This granular alluvium appears to pinch
out to the northeast of Site 14. Geotechnical samples collected below the water table in the 20- to 24-foot
bgs range consisted of 70 to 80 percent sand with relatively high effective porosities (15 to 18 percent);
however, these sandy soils are not representative of soils in the Site 14 vadose zone, where the vapor
probes for this investigation were installed. Rather, the vadose zone predominantly consists of silts and
clays. Limited soil physical property data for the vadose zone and A-zone (aquifer) soils at Site 14 are
presented in Table 2-2.
Table 2-2
Typical Physical Properties of the Vadose Zone and A-zone Aquifer
PARAMETER
Clay (%)
Dry Bulk Density ( lbs/ft3)
Bulk Density ( lbs/ft3)
Moisture Content (%)
Fraction Organic Carbon (%)
Percent Gravel (%)
Percent Sand (%)
Percent Silt Or Percent Clay (%)
Porosity, Effective
Porosity, Total
Permeability, Effective (millidarcy)
USCS Classification (field)
Geotechnical Analysis Classification
RESULT
Vadose zone
12-37
0.28-0.48
0.45-0.60
4.3-3.7
Clay and silt
A-zone
4.2-6.1
95.5-95.9
113.4-113.5
18.3-18.8
0.80-0.90
0.0-0.6
73-80
19.7-27.1
0.15-0.18
0.40-0.41
medium sand
silty sand
Note:
lbs/ft3 - pounds per cubic foot
Beneath the A-zone are the B-, C-, D- and E-zones. Thick sand deposits are found in the B-, C-, and D-
zones, particularly in the center of Site 14. The other two extensive clay layers beneath the site are the C-
and E-Clays. The C-Clay is about 250 feet bgs and the E-Clay about 680-720 feet bgs. The E-Clay
extends throughout the central valley and is also called the Corcoran Clay. The E-Clay is the major
confining unit in the valley and separates the two regionally defined aquifers: the Lower Confined
aquifer and the Upper Unconfmed to Semi-confined aquifer. The C- and E-Clay are not discussed further
as they lie well below the depth of interest to this study. The A-zone groundwater is the uppermost
groundwater in the Upper Unconfmed to Semi-confined aquifer. All three of the clay layers are
lacustrine.
In general, the hydrogeology of the shallow-upper aquifer beneath IRP Site 14 (the A-zone) can be
characterized as a heterogeneous alluvial aquifer with a relatively flat water table and limited vertical
connection to underlying aquifer zones.
The quality of the shallow groundwater is generally poor because of elevated salinity that is likely a result
of irrigation practices in an arid environment. For example, sulfate concentrations above 10,000
milligrams per liter (mg/L) are not uncommon at NAS Lemoore.
2-5
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TCE CONCENTRATIONS
ATMW14-70A(|jg/l)
W14-267A
0.2 U
Jun-01
Oct-01
Sep-05
Mar-06
Oct-06
Jan-07
Apr-09
MWI4-
56 ^
MW14-276E*
REGIONAL
GROUNDWAT
FLOW DIRECTION
MW14-67D
*MW14-251A
0.2 U
MW14-68A
*
MW14-273C
O
MW14-47A
32
4-63
BIDONED)
\\v
\\ VA^^" MW14-260E
MW14-261£-
MW14-269A
1,400
MW14-I53A
MW14-262E
MW14-252A
0.2 U
MW14-256E
MW14-254B
AIRCGrAFl PARKING
MW14-2
(DESTROY
MW14-271B
HW14-55A
220
MW14-255C
MW14-B2\(B,C
MW14-257B
MW14-263E
MW14-10A
-2
0.2 U
MW14-50A
7.2
MW14-03A
*
MW14-71A
120
MW14-43A
0.2 U
UMW14-54A
3.6
AMW14-12A
LEGEND
so STORM DRAIN AND LATERALS
DECK DRAIN
AIRCRAFT SERVICE CONDUIT
-IWL INDUSTRIALWASTEWATER LINE
REGULARLY OCCUPIED BUILDING
MONITORING WELL
TCE CONTOUR ("A" ZONE) IN ^g/L, DASHED
IN AREAS OF GREATER UNCERTAINTY
VAPOR PROBE TRANSECT
WELL DEPTH DESIGNATIONS
(A ZONE)
B = 45-60 FEET BGS
C = 60-75 FEET BGS
D = 75-95 FEET BGS
E = > 95 FEET BGS
60' 0 60' 120'
^^S^^E
SCALE: 1" = 120'
MAS Lemoore - Sites 5/9 and 14
U.S. Navy, NAVFAC Southwest, San Diego, California
FIGURE 2-3
TRICHLOROETHENE PLUME
IN THE A ZONE
APRIL 2009
STREAMS T085
It
TETRA TECH
-------
2.1.2 Chlorinated Solvent Plume Conditions
Groundwater monitoring results for TCE obtained in April 2009 are presented on Figure 2-3. TCE is the
primary chemical of concern in groundwater. The most significant concentrations (above 1,000
micrograms per liter [|ig/L]) are found adjacent to and east of Building 180; however, this is a high-traffic
area used for aircraft parking and consists of an excessively thick (18 to 24 inches) concrete slab; both of
these factors rendered the area unsuitable for this study. The area used for this investigation was adjacent
to and southeast of Building 170. TCE was measured in groundwater from monitoring well MW14-70A,
located in the study area, at a concentration of 320 (ig/L in April 2009, continuing a trend of increasing
concentrations observed since June 2001 (Figure 2-3). TCE concentrations in samples from groundwater
wells installed along the sampling transect used for this investigation ranged from non-detect to 830 (ig/L
from November 2008 to October 2009. The locations of well MW14-70A and the sampling locations for
this study (designated ST-1 through ST-9) are shown on Figure 2-4.
2.1.3 Selection of IRP Site 14
Site 14 was previously selected as a suitable location to conduct an investigation of soil vapor profiles
under Task Order (TO) 65 for the following reasons: (1) it provides a study area over a well-defined,
shallow, chlorinated-solvent plume in groundwater, (2) a variety of buildings with slab-on-grade
foundations are present at the site, and (3) Tetra Tech has an established working relationship with the
environmental program staff at NAS Lemoore. This investigation was an extension of the work
conducted under TO 65.
2.2 SOIL VAPOR PROBE TRANSECTS
The following paragraphs summarize the installation of the soil gas probe array at IRP Site 14. Details of
the drilling and probe installation activities are presented in the TO 65 project report (EPA 2009) and the
Sampling Trip Report (Appendix A).
Two transects of six soil vapor sampling probes were installed for TO 65 in January and February 2008.
The transects were designated as the south (primary) transect and north (secondary) transect, with the
sampling locations designated ST-1 through ST-6 and NT-1 through NT-6, respectively (Figure 2-4).
The transects were placed such that locations ST-1, ST-2, NT-1, and NT-2 were on the concrete slab
adjacent to Building 170, and the remaining locations were in the uncovered area to the east. In October
2008, three additional sampling locations (ST-7 through ST-9) were established to provide additional data
at key locations (Figure 2-4). For this investigation, only south transect locations ST-1 through ST-5 and
ST-7 through ST-9 were used. VOCs were not detected at location ST-6 during the TO 65 investigation;
therefore, it was excluded from this study. At each of the sampling locations, soil vapor probes were
installed at 2, 4, 7, and 10 feet bgs. At locations ST-1, ST-2, ST-7, and ST-8, subslab soil vapor probes
were installed immediately below the concrete pad.
Two types of vapor probes were installed and utilized for this investigation. These are referred to here as
"macro-purge" vapor probes and "micro-purge" vapor probes as discussed below.
2.2.1 Macro-Purge Vapor Probes
The macro-purge probes were installed in pilot holes advanced to 10 feet bgs, or to groundwater at depths
between 10.7 and 11.5 feet bgs, using a direct push rig. Soils encountered in the pilot holes consisted
primarily of silty sands, clayey sands, and clays. Soil samples were collected at the vapor probe depths of
2, 4, 7, and 10 feet bgs in each of the three pilot holes drilled in October 2008 (ST-7 through ST-9).
2-7
-------
LEGEND
NT-5
A
ST-4
(0%
SOIL VAPOR PROBE LOCATION (NOT USED FOR THIS STUDY)
SOIL VAPOR PROBE WITH COLLOCATED GROUNDWATER WELL
(GROUNDWATER TCE CONCENTRATION IN PARENTHESES)
A- IRP GROUNDWATER WELL (GROUNDWATER TCE CONCENTRATION
IN PARENTHESES)
X FENCE LINE
UNPAVED AREA
SECONDARY
TRANSECT
NT-6
A
NT-5
A
ST-6
A
PRIMARY
TRANSECT
ST-4
ST-5
©
(ND)
ST-9
ST-
ST-3
ST8 ^
ST-1 ,© N(66)
© (140)
ST-7 (360)'
(510)
(320)
NASLemoore-Site14
U.S. Navy, NAVFAC Southwest, San Diego, California
FIGURE 2-4
SOIL VAPOR PROBE TRANSECTS AND
APRIL 2009 GROUNDWATER
TCE CONCENTRATIONS (|jg/L)
STREAMS TO 85
Tetra Tech EM Inc.
-------
Macro-purge soil vapor probes were constructed as follows. Approximately 3 inches of #2/12 sand was
poured into the bottom of the pilot holes. A 1-inch long gas-permeable membrane sampling probe,
attached to 1/8-inch diameter Nylaflow tubing, was then lowered through the drill rod to the top of the
sand. Additional sand was then poured around the sampling probe until it extended approximately 2
inches above the membrane to form an approximately 6-inch long sand pack around the sampling probe.
Approximately 12 inches of dry bentonite was then placed on top of the sand pack, followed by hydrated
bentonite to approximately 3 inches below the next sampling depth (i.e. 7 feet bgs). This process was
repeated to install four nested soil vapor probes, at depths of 2, 4, 7, and 10 feet bgs, in each pilot hole.
At locations on the concrete pad, the subslab vapor probes were installed in the same way, but in a
separate, 1-inch diameter hole that was drilled through the concrete with an electric hammer drill. A total
of 36 vapor probes were used for this investigation (four subslab probes and 32 deep probes). The
sampling probes were completed at the surface with approximately 18 inches of Nylaflow tubing
extending out of the ground and a luer valve fitted to the end of the tubing. A schematic diagram of the
probe installations is provided in Figure 2-5.
The individual probes were identified by the location ID and the depth separated by a dash (e.g., the probe
installed at 4 feet bgs at location ST-1 is designated ST1-4). The subslab probes were identified with the
location ID and "SS" (e.g. ST1-SS). Table 2-3 provides a summary of the probe installation details.
2.2.2 Micro-Purge Vapor Probes
Concurrently with the installation of the macro-purge vapor probes, EPA installed micro-purge vapor
probes. Micro-purge vapor probes were collocated with the macro-purge vapor wells at locations ST-1
through ST-4, and ST-7 through ST-9 at depths of 2, 4, 7, and 10 feet bgs (total of 28 probes). The lateral
distance between micro-purge probes and the corresponding nested macro-purge probes varied between
approximately 6 inches and 2 feet. Subslab micro-purge vapor wells were not installed. The micro-purge
vapor probes consisted of 0.01-inch inner diameter (ID) stainless steel tubing epoxied into steel point
holders. The stainless steel tubing was threaded through the drill-rods, which were driven to the target
sampling depth using the EPA-operated direct-push rig. Upon reaching the target depth, the drill rod was
pulled up approximately 1 inch to expose the drop-off point to the vadose zone. The drill rods were left
in place during sampling in order to seal out ambient air; thus micro-purge probes at multiple depths were
installed in separate boreholes, rather than being nested in a single boring, and the probe rods were left in
place for the duration of the project.
2.2.3 Groundwater Monitoring Wells
For this investigation, groundwater monitoring wells were installed immediately adjacent to vapor probe
locations ST-1 through ST-5 and ST-7 through ST-9. The wells were installed in boreholes drilled
approximately 2 feet below the water table using a direct-push drill rig. The wells were constructed using
0.75-inch diameter polyvinylchloride (PVC) well casing and screen. The screen and casing was placed in
the open borehole so that approximately 1 foot of well screen was above the water table and 2 feet were
below. Clean #2/12 sand was then poured down the annular space to form a filter pack to approximately
1 foot above the well screen. The wells were sealed to the surface with hydrated bentonite and completed
at the surface in flush-mount, traffic rated well boxes. The relatively short (i.e., 3 feet long) well screens
were used in order to obtain groundwater samples that are representative of the conditions near the top of
the water column.
2-9
-------
Table 2-3
Macro-Purge Soil Gas Probe Installation Details
Location
ID
ST-1
ST-2
ST-3
ST-4
ST-5
ST-7
ST-8
ST-9
Probe ID
ST1-SS
ST1-2
ST1-4
ST1-7
ST1-10
ST2-SS
ST2-2
ST2-4
ST2-7
ST2-10
ST3-2
ST3-4
ST3-7
ST3-10
ST4-2
ST4-4
ST4-7
ST4-10
ST5-2
ST5-4
ST5-7
ST5-10
ST7-SS
ST7-2
ST7-4
ST7-7
ST7-10
ST8-SS
ST8-2
ST8-4
ST8-7
ST8-10
ST9-2
ST9-4
ST9-7
ST9-10
Installation Date
February 11,2008
February 11,2008
January 18, 2008
January 22, 2008
January 22, 2008
October 22, 2008
October 22, 2008
October 22, 2008
Easting
6283734.19
6283748.25
6283753.98
6283771.04
6283789.04
6283723.72
6283739.86
6283761.65
Northing
2002852.99
2002859.41
2002860.26
2002870.24
2002878.29
2002848.69
2002857.26
2002866.30
Probe
Depth
(feet bgs)
Subslab
2
4
7
10
Subslab
2
4
7
10
2
4
7
10
2
4
7
10
2
4
7
10
Subslab
2
4
7
10
Subslab
2
4
7
10
2
4
7
10
Length of
Sand pack
(inches)
2
6
6
6
6
2
6
6
6
6
6
6
6
6
6
6
6
6
6
6
6
6
2
6
6
6
6
2
6
6
6
6
6
6
6
6
System
Volume
(mL)
2
o
J
5
8
11
2
3
5
8
11
3
5
8
11
3
5
8
11
3
5
8
11
2
o
J
5
8
11
2
3
5
8
11
3
5
8
11
Definitions:
bgs - below ground surface
mL - milliliters
2.3
EXPERIMENTAL DESIGN
The primary objectives of this investigation were to: (1) assess the vertical distribution of VOCs in soils
from groundwater to the subslab/near-surface environment, and (2) assess the long-term variability in the
distribution of VOCs. Secondary objectives were to compare data obtained from the macro-purge probes
to data obtained from the micro-purge probes and to evaluate the effect of sampling parameters (e.g.
purge rate, purge volume, and sample volume) on measured VOC concentrations.
2-10
-------
1/8-INCH OD
NYLAFLOW TUBING
2-WAY
LUER VALVE
T
SURF
B
0
'ACE
X
I
^ f
.c ^
c
:;
!i
: _ :'
'.'.
^\
SWAGELOK^. ^CONCRETE
FITTING \ /
/ ' /
/ 7 /
/ 7 /
/ 7 /
/ 7 /
/ 7 /
/ 7 /
/ 7 /
/ 7 /
/ 7 /
/ 7 /
/ 7 /
||
_ ;> o j
.'.:.'.:'.
II
'n'ci'. -S
II
.^? i
?=.'.' z ^ ^°_ ^^
:':--' ^-HYDRATED G
9 BENTONITE
TA° rrr?MrAr)i r ' '*
oAo rCKI ICAdLC ^v.
PROBE TIP ^^CLEAN SAND
PACK
SUB-SLAB
PROBE
PA° ^^^^/l^A^l r
bAo rLKrILADLL
PROBE TIP
-« HYDRATED
GRANULAR
BENTONITE
* DRY GRANULAR
BENTONITE
-* CLEAN SAND
PACK
NOT TO SC/
MAS Lemoore-Sit
U.S. Navy, NAVFAC Southwest, S
FIGURE 2-5
NESTED SOIL-GAS PROBES
SOIL VAPOR PROBE
CONSTRUCTION SCHEMATIC
STREAMS TO 85
Tetra Tech EM Inc.
-------
To achieve the project objectives, the macro- and micro-purge soil gas probes and the groundwater
monitoring wells described in Section 2.2 were sampled on a monthly basis from November 2008 through
October 2009. Thus, approximately 36 macro-purge vapor samples, 28 micro-purge vapor samples, and
eight groundwater samples were collected each month for 12 months. This provided a large database of
measured VOC concentrations in groundwater and soil vapor to assess the distribution of VOCs, examine
the variability of VOC concentrations over the course of a year, and compare measurements from
collocated macro-purge and micro-purge vapor probes.
In addition, during the May 2009 sampling round, a subset of the macro-purge probes were used to
evaluate the effect of sampling parameters on measured VOC concentrations. For this study, multiple
samples were collected from a single probe while varying the purge rate, purge volume, or sample
volume. Details of the methodology and the results of the sampling parameters evaluation are presented
in Appendix B.
2-12
-------
3.0 EQUIPMENT AND METHODS
The following sections describe the sampling and analysis procedures used during the investigation.
3.1 SAMPLE COLLECTION
3.1.1 Soil Samples
Intact soil cores were retrieved from the ST-7 through ST-9 pilot boreholes in clear, acetate sleeves used
as liners in the drill rod. Soil sample aliquots for VOC analyses were collected from the acetate sleeves
and transferred directly to VOA vials containing methanol and sodium bisulfate preservatives in
accordance with EPA SW-846 Method 5035 (EPA 1996). Soil samples were submitted to American
Environmental Testing Laboratory, Inc. (AETL), located in Burbank, California for VOC analysis via
EPA SW-846 Method 8260B (EPA 1997).
3.1.2 Soil Vapor Samples
Active soil gas sample collection consists of two primary components. The first is purging the probe to
remove ambient air and any other gases not representative of subsurface conditions at the target sampling
depth. The second is collection of the soil gas sample into an appropriate container for transfer to the
analytical instrument. Based on the results of purge tests conducted at the probes during the TO 65
investigation (EPA 2009) and the results of the TO 05 investigation (EPA 2007), the volume of gas
removed from each probe prior to sampling (the purge volume) was set at three system volumes. A
system volume is the volume of the gas permeable tip plus the tubing but not the sand pack. The sand
pack was excluded from the system volume calculation because the probes had ample time (minimum of
3 weeks) to equilibrate, and so it was assumed the sand pack pore space was in equilibrium with the
surrounding native soils. The system volumes for the macro-purge probes are provided in Table 2-3.
Probes were purged at a rate of approximately 200 milliliters per minute (mL/min). The sample volume
from macro-purge probes was set at 20 mL, and the samples were collected in 60-mL glass syringes.
Samples from micro-purge soil gas probes were collected in 10-mL glass syringes. System volumes of
the micro-purge probes were 2.025 mL for the 2-foot probes, 2.075 mL for the 4-foot probes, 2.125 mL
for the 7-foot probes, and 2.150 mL for the 10-foot probes. Three system volumes were purged from
each micro-purge soil gas probe prior to collecting a 2.5-mL sample. Soil gas samples were analyzed on-
site in a mobile laboratory operated by H&P Mobile Geochemistry (HPMG).
Samples were collected on a monthly basis from the probes as outlined in Table 3-1. During each
monthly sampling round, an attempt was made to collect a vapor sample from each of the probes (36
macro-purge probes and 28 micro-purge probes); however, during the course of the investigation, some of
the micro-purge probes became clogged and could no longer be sampled (Table 3-1).
Following the monthly sampling round in May 2009, the sampling parameters study was conducted. For
this study, a subset of the probes was sampled using varying purge rate, purge volume, and sample
volume to assess whether these parameters affect the measured VOC concentrations. Details of the
sampling approach are provided in Appendix B.
3.1.3 Groundwater Samples
Groundwater samples were collected during each monthly sampling round from each of the eight
monitoring wells installed along the transect, with the exception of the August 2009 sampling round,
when wells ST-4 and ST-5 were dry (Table 3-1). The wells were purged using a peristaltic pump at a rate
3-1
-------
of approximately 100 mL/min until either three well volumes were removed or the well went dry. The
samples were then collected using 0.5-inch diameter disposable bailers and transferred to hydrochloric
acid preserved volatile organic analysis vials and sent to the HPMG fixed laboratory in Carlsbad,
California for VOC analysis using EPA SW-846 Method 8260B.
Table 3-1
Summary of Monthly Sampling Rounds
Round
November 2008
December 2008
January 2009
February 2009
March 2009
April 2009
May 2009
June 2009
July 2009
August 2009
September 2009
October 2009
Dates
11/12-11/14
12/15 - 12/17
1/19 - 1/20
2/17-2/18
3/16-3/18
4/22 - 4/23
5/18
6/15-6/16
7/14-7/15
8/11-8/12
9/15
10/13 - 10/14
Number of
Macro-Purge
Samples
33
36
36
36
36
35
34
33
29
25
23
19
Number of
Micro-Purge
Samples
28
26
28
28
28
27
26
25
22
22
22
21
Number of
Groundwater
Samples
8
8
8
8
8
8
8
8
8
6
8
8
3.2
Notes:
Numbers of samples do not include quality control duplicates
MOBILE LABORATORY
Soil gas samples collected for this investigation were analyzed on-site using a mobile laboratory operated
by HPMG. Details of the analytical method, equipment, and detection limit (DL) are provided below.
3.2.1 Analytical Method
Soil gas samples were analyzed by direct injection using a modified version of EPA SW-846 Method
8021 (EPA 1996). Method 8021 is a gas chromatography method using a photoionization detector (PID)
and a Hall Detector (electrolytic conductivity detector). The modification for this program was
replacement of the Hall Detector with an electron capture detector (ECD). This method is faster, more
sensitive, and has a larger linear dynamic operating range than gas chromatography/mass spectrometry
(GC/MS) methods. The contaminants of concern at IRP Site 14 (i.e., TCE and PCE) had been previously
identified based on IRP investigation data (Section 2.1.2); therefore, the compound identification
advantages of GC/MS were not warranted. The target compound list for this project was limited to TCE
and PCE.
EPA Method TO-14/TO-15 was not suitable for this investigation because the minimal flow rates and
sample volumes required for the micro-purge probes precluded the use of the TO methods. The TO
methods require the use of Summa canisters and the smallest readily available Summa canisters have a
volume of 500 mL. As the sample volumes collected from the micro-purge probes were approximately
2.5-mL, it would not have been possible to sample with Summa canisters. In addition, the experimental
design called for the analysis of approximately 70 vapor samples a month (including duplicates). Using
Method 8021, with an analysis time of approximately 3 minutes, this was achievable in two field days on-
site. Typical costs for TO-15 analysis at a commercial laboratory are on the order of $250/sample,
3-2
-------
including Summa rental. Collection and analysis of 70 vapor samples would have; therefore, been
prohibitively expensive.
Soil gas samples collected during this investigation were flushed through a 1 cc gas sampling valve and
direct injected into the instrument. The sample syringes were flushed several times with clean air and
allowed to aerate between samples.
The analyses were performed following EPA SW-846 Method 8000 protocols, modified for soil gas.
Modifications from the EPA method consisted of the project-specific analyte list, absence of matrix spike
samples and surrogates, and changes in calibration protocols as discussed in Section 3.3.2.
1.1.1 Equipment
The following equipment was utilized by the mobile laboratory for this project.
Instrument: SRI 8610 Gas Chromatograph.
Column: 30 meter DB-61, megabore capillary.
Carrier flow: Nitrogen at 10 mL/min.
Detectors: PID and BCD.
Column oven: 80° C isothermal.
1.1.2 Detection Limits
The detection limit for the target compounds was 5 (ig/m3.
1.2 QUALITY ASSURANCE/QUALITY CONTROL
1.2.1 Field Quality Control Protocols
A subset of the soil vapor sampling probes were leak checked during the TO 65 investigation by placing a
cloth rag in a plastic bag, saturating the rag with 1,1-difluoroethane (DFA), placing the bag over the
surface completion of the probe, and then purging the probe normally and collecting a sample. None of
the probes failed the leak test; therefore, because all probes were installed using the same procedures, it
was assumed that all probes were sufficiently sealed.
Purge volume tests were conducted to determine the optimum volume of gas to purge from each probe
prior to sample collection. Purge tests were conducted on probes ST1-10, ST2-10, and ST3-10. The
purge tests consisted of purging one or two system volumes and then collecting a sample, purging another
one or two system volumes (for a total of two or three) and collecting a sample, and purging another two
or three system volumes (for a total of five), and collecting a sample. The results of the purge volume
tests did not convincingly indicate that any tested purge volume was superior to the others. Therefore, the
default 3 system volume purge was used for subsequent sampling.
Field duplicate vapor samples were collected to measure the reproducibility and precision of the total
sampling system. Field duplicate samples were collected at a rate of approximately 9 percent. Of the 67
field duplicate vapor samples collected during the program, only seven exceeded the Quality Assurance
Project Plan (QAPP) (Tetra Tech 2008a, b) specified criterion of ±40 relative percent difference (RPD).
A summary of the duplicate results for soil gas samples is provided in Table 3-2.
3-3
-------
Table 3-2
Summary of Soil Gas and Groundwater TCE Duplicate Results
Round
Collection
Date
Sample ID
Primary
Concentration
Duplicate
Concentration
RPD
Macro-Purge Samples (jig/m3)
November 2008
November 2008
November 2008
November 2008
December 2008
December 2008
December 2008
December 2008
January 2009
January 2009
January 2009
February 2009
February 2009
February 2009
March 2009
March 2009
March 2009
March 2009
March 2009
April 2009
April 2009
May 2009
May 2009
May 2009
June 2009
June 2009
June 2009
June 2009
June 2009
July 2009
July 2009
July 2009
July 2009
July 2009
August 2009
August 2009
September 2009
October 2009
October 2009
October 2009
October 2009
13-Nov-08
13-Nov-08
13-Nov-08
13-Nov-08
17-Dec-08
17-Dec-08
17-Dec-08
17-Dec-08
20-Jan-09
20-Jan-09
20-Jan-09
18-Feb-09
18-Feb-09
18-Feb-09
17-Mar-09
17-Mar-09
17-Mar-09
17-Mar-09
18-Mar-09
22-Apr-09
22-Apr-09
18-May-09
18-May-09
18-May-09
16-Jun-09
16-Jun-09
16-Jun-09
16-Jun-09
16-Jun-09
14-M-09
14-M-09
14-M-09
14-M-09
14-M-09
12-Aug-09
12-Aug-09
15-Sep-09
14-Oct-09
14-Oct-09
14-Oct-09
14-Oct-09
ST1-7
ST7-SS
ST3-10
ST1-4
ST4-10
ST5-10
ST1-10
ST2-2
ST1-4
ST4-10
ST7-7
ST1-10
ST4-10
ST7-7
ST2-10
ST2-4
ST3-2
ST8-2
ST7-4
ST3-10
ST2-SS
ST7-SS
ST9-7
ST1-10
ST7-2
ST8-4
ST7-10
ST3-7
ST2-10
ST3-7
ST4-10
ST2-SS
ST9-10
ST7-SS
ST9-4
ST3-10
ST3-10
ST2-SS
ST3-10
ST4-10
ST8-2
56,000
4,400
60
37,600
ND
48
103,000
71
30,000
ND
130,000
5,3000
ND
130,000
3,100
1,200
ND
12,000
130,000
87
ND
4,000
21
66,000
100,000
34,000
170,000
520
2,400
1,100
ND
83
206
114
63
530
2,000
1,100
1,100
24
19,000
49,000
4,000
46
38,400
ND
21
93,000
74
49,000
ND
140,000
52,000
ND
130,000
3,100
1,200
ND
12,000
136,000
77
ND
3,800
23
71,000
100,000
32,000
150,000
520
2,200
1,090
ND
22
230
39
65
490
2,300
1,100
1,300
110
14,000
13%
10%
26%
2%
78%
10%
4%
48%
7%
2%
0%
0%
0%
0%
5%
12%
5%
9%
7%
0%
6%
13%
0%
9%
1%
116%
11%
98%
3%
8%
14%
0%
17%
128%
30%
3-4
-------
Table 3-2 (continued)
Round
Collection
Date
Sample ID
Primary
Concentration
Duplicate
Concentration
RPD
Micro-Purge Samples (jig/m3)
November 2008
November 2008
December 2008
December 2008
December 2008
January 2009
January 2009
January 2009
February 2009
February 2009
February 2009
February 2009
February 2009
March 2009
March 2009
March 2009
May 2009
April 2009
April 2009
April 2009
May 2009
May 2009
April 2009
June 2009
June 2009
June 2009
June 2009
September 2009
14-Nov-08
14-Nov-08
16-Dec-08
17-Dec-08
17-Dec-08
20-Jan-09
20-Jan-09
20-Jan-09
18-Feb-09
18-Feb-09
18-Feb-09
18-Feb-09
18-Feb-09
18-Mar-09
17-Mar-09
17-Mar-09
18-May-09
22-Apr-09
22-Apr-09
22-Apr-09
18-May-09
18-May-09
22-Apr-09
16-Jun-09
16-Jun-09
16-Jun-09
16-Jun-09
15-Sep-09
ST7MP-7
ST7MP-10
ST7MP-7
ST8MP-2
ST9MP-7
ST8MP-4
ST2MP-7
ST3MP-4
ST7MP-2
ST9MP-7
ST8MP-10
ST2MP-10
ST3MP-7
ST1MP-7
ST4MP-2
ST9MP-2
ST3MP-10
ST4MP-2
ST4MP-10
ST7MP-10
ST7MP-10
ST8MP-10
ST9MP-4
ST2MP-4
ST4MP-10
ST8MP-2
ST8MP-10
ST3MP-7
87,000
53,000
27,500
2,400
28
7,600
1,220
ND
26,000
ND
11,000
105
135
94,000
10
14
99
ND
11
22,000
46,000
7,800
ND
2,700
ND
4,800
2,800
3,000
108,000
56,000
26,600
2,600
32
7,900
1,320
ND
29,000
ND
11,200
168
132
110,000
15
33
110
ND
ND
16,000
52,000
8,400
ND
3,500
ND
4,400
3,200
3,500
22%
6%
3%
8%
13%
4%
8%
11%
2%
46%
2%
16%
40%
81%
11%
200%
32%
12%
7%
26%
9%
13%
15%
Groundwater Samples (jig/L)
November 2008
December 2008
January 2009
February 2009
March 2009
April 2009
June 2009
July 2009
August 2009
September 2009
13-Nov-08
15-Dec-08
19-Jan-09
17-Feb-09
16-Mar-09
23-Apr-09
15-Jun-09
15-Jul-09
ll-Aug-09
15-Sep-09
ST4-GW
ST7-GW
ST7-GW
ST7-GW
ST7-GW
ST7-GW
ST7-GW
ST7-GW
ST7-GW
ST7-GW
0.81J
470
460
460
380
510
670
830
640
490
ND
490
450
450
340
440
480
830
690
360
NA
4%
2%
2%
11%
15%
33%
0%
8%
31%
Definitions:
J -estimated concentration
|ig/L -micrograms per liter
Hg/m3 -micrograms per cubic meter
NA -not applicable
ND -not detected; result is less than the detection level
RPD -relative percent difference
TCE -trichloroethene
3-5
-------
A total of 94 groundwater samples plus 10 duplicates were collected over the 12 sampling rounds. All of
the RPD results for the duplicates were within the QAPP specified criterion of ±40 RPD (Table 3-2).
One field duplicate soil sample was analyzed for the set of 12 field samples analyzed. The only analyte
detected in the soil sample was TCE. The RPD between the primary and duplicate samples was 22
percent.
3.3.2 Mobile Laboratory Quality Control Protocols
Example calibration data and chromatograms are provided in Appendix C. The laboratory data packages
for the entire project are on file at the HPMG offices.
3.3.2.1 Laboratory Data Logs
The field chemist maintained analytical records, including date and time of analysis, sampler's name,
chemist's name, sample identification number, concentrations of compounds detected, calibration data,
and any unusual conditions.
3.3.2.2 Instrument Calibration
An initial 4-point calibration curve was performed at the start of each monthly sampling round. EPA
method 8000 requires the use of five levels for an initial calibration curve; however, existing soil gas
guidance from the California Environmental Protection Agency (Cal/EPA) Department of Toxic
Substances Control (DTSC 2003) only requires three calibration levels. A linearity check of the
calibration curve for each compound was performed by computing a correlation coefficient and an
average response factor.
Continuing calibration verification samples were analyzed a minimum of once per sampling day as
specified in the QAPP (Tetra Tech 2008a, b). These standards were prepared from a traceable source at
the middle concentration of the calibration curve. Acceptable continuing calibration agreement was set at
±20 percent to the average response factor from the calibration curve.
A significant spike in both TCE and PCE concentrations was observed in the September 2009 soil vapor
data; therefore, the calibration data from the September 2009 sampling round were reviewed to determine
if the observed spike might be related to a problem with the calibration. The response factors from the
calibration standards for the PID in September were about 2.5 times lower than the average of the August
and October sampling rounds. The August and October response factors agreed within 30 percent. PIDs
are extremely stable detectors so a shift in response of 2 to 3 times from one month to the next and then
back again is atypical. It was subsequently determined that the working calibration standards for
September were not made from the source calibration gas cylinder as was done for all the other rounds.
Rather, an aliquot of the source standard was down-filled into a smaller container and transported to the
on-site lab. The working standards were then made using the calibration gas from the smaller canister.
While this procedure should have been satisfactory, there was no analysis of the concentration of the gas
in the smaller canister after it was filled and; hence, it is possible that the concentration was not at the
source concentration of 1000 parts per billion by volume (ppbV) for TCE and PCE. If this was the case, a
lower concentration standard would yield lower response factors. Lower response factors yield higher
reported concentrations for the same sample concentration. Since the increase in concentrations reported
in the September sampling round were approximately a factor of 2 to 3, it raises doubt over the accuracy
of the data for this round.
3-6
-------
3.3.2.3 Blanks
Laboratory blanks were analyzed at the start of each sampling day. All of the blank sample results were
non-detect for all compounds.
3.3.3 Project QAPP Deviations and Additions
During the course of implementing the program, several deviations occurred from the specifications in the
QAPP (Tetra Tech 2008a, b). Specific deviations are listed below.
The primary deviation from the QAPP was the analysis of soil vapor samples on-site using the
mobile laboratory rather than sending the samples to an off-site laboratory. The QAPP stated that
the soil vapor samples would be collected in evacuated head-space vials and shipped to HPMG's
fixed laboratory for analysis. However, it was subsequently determined that the samples could be
analyzed on-site in the mobile laboratory as a cost effective and technically superior alternative.
This change was made with the prior approval of EPA and resulted in significantly better data as
it eliminated potential concerns related to holding times and also allowed for the re-collection/re-
analysis of samples when anomalous results were obtained.
The QAPP stated that a total of 68 soil vapor probes would be sampled each month. This was
based on the assumption that there would be collocated micro-purge probes with each macro-
purge probe (with the exception of the sub-slab probes). However, due to the consistent non-
detect results at ST-5, EPA removed the micro-purge probes from this location; therefore, a total
of 64 probes (36 macro-purge and 28 micro-purge) were sampled each month.
The QAPP stated that matrix spike/matrix spike duplicate (MS/MSD) groundwater samples
would be analyzed every other month; however, MS/MSDs were run every month.
3-7
-------
4.0
RESULTS AND DISCUSSION
4.1
DATA SUMMARY
4.1.1 Soil Sample Results
Soil samples were collected on October 22, 2008 from locations ST-7, ST-8, and ST-9 at depths of 2, 4, 7,
and 10 feet bgs and analyzed for VOCs. TCE was detected in the samples from locations ST-7 and ST-8,
but not in any of the samples from ST-9. The results are summarized in Table 4-1 with the collocated
vapor sample concentrations measured in November 2008. While there was a general tendency for higher
vapor concentrations to be associated with higher soil concentrations, the correlation was not a strong or
predictive one.
Table 4-1
Summary of TCE Concentrations in Soil (ug/kg)
Location
ST-7
ST-7
ST-7
ST-7
ST-7
ST-8
ST-8
ST-8
ST-8
ST-9
ST-9
ST-9
ST-9
Depth
(ft bgs)
2
4
4
7
10
2
4
7
10
2
4
7
10
Sample
ST7-2
ST7-4
ZDUP 10
ST7-7
ST7-10
ST8-2
ST8-4
ST8-7
ST8-10
ST9-2
ST9-4
ST9-7
ST9-10
Soil
Result
25.1
62.2
50
16.7
36.8
4.8
13.8
2.9
13.7
ND
ND
ND
ND
DL
0.5
0.5
0.5
0.5
0.5
0.5
0.5
0.5
0.5
0.5
0.5
0.5
0.5
Vapor1
jig/m3
40,000
60,000
NA
92,000
165,000
4,450
8,300
14,700
30,000
24
46
44
315
Notes:
1 - Vapor sample collected 11/13/2008, results in |ig/m
DL - detection level
ft bgs - feet below ground surface
Hg/kg - micrograms per kilogram
Hg/m3 - micrograms per cubic meter
NA - not applicable
ND - not detected
TCE - trichloroethene
4.1.2 Groundwater Sample Results
Groundwater samples were collected from each well on a monthly basis from November 2008 through
October 2009 with the exception of wells ST-4 and ST-5, which did not contain sufficient water to sample
in August 2009. TCE, PCE, 1,1-DCA, 1,1-DCE, c/s-l,2-DCE, benzene, toluene, naphthalene,
chloroform, and chloromethane were detected in groundwater samples; however, of these, only TCE and
c/s-l,2-DCE were detected at concentrations above 10 (ig/L, and the maximum measured concentration of
c/s-l,2-DCE was 26 (ig/L. In contrast, TCE was measured at concentrations up to 830 (ig/L. The
complete groundwater sample results are provided in Appendix D and the TCE concentrations are
summarized in Table 4-2.
4-1
-------
Table 4-2
Summary of TCE Concentrations in Groundwater (ug/L)
Sample
Date
13-Nov-08
15-Dec-08
19-Jan-09
17-Feb-09
16-Mar-09
23-Apr-09
18-May-09
15-Jun-09
15-Jul-09
ll-Aug-09
15-Sep-09
13-Oct-09
Monitoring Well Location1
RL
1.0
1.0
1.0
1.0
1.0
1.0
1.0
1.0
1.0
1.0
1.0
1.0
ST-7
500
470
460
460
380
510
510
670
830
640
490
400
ST-1
310
420
420
310
320
360
330
390
430
280
300
360
ST-8
190
190
150
150
110
140
160
160
210
70
130
130
ST-2
82
85
67
74
66
66
67
75
93
52
56
35
ST-3
40
45
32
34
32
28
35
32
37
28
27
22
ST-9
12
9.6
8.7
7.6
5.9
6.5
7.7
7.0
7.0
5.7
7.6
5.8
ST-4
0.81J
0.84J
0.69J
0.6J
0.5J
0.5J
0.6J
0.6J
0.4J
NS
0.6J
0.5J
ST-5
ND
ND
ND
ND
ND
ND
ND
ND
ND
NS
ND
ND
Notes:
1 - Well locations arranged from west to east
J - The result is an estimated concentration below the reporting limit.
Hg/L - micrograms per liter
ND - not detected
NS - not sampled
RL - reporting limit
TCE - trichloroethene
Table 4-2 is arranged with the sampling locations listed from west to east. Locations ST-1, ST-2, ST-7,
and ST-8 are on the concrete slab, while the remaining locations are on uncovered ground (Figure 4-1).
The groundwater concentrations decrease along the transect from west to east. Table 4-3 shows the
percent difference in TCE concentrations between adjacent sampling locations divided by the distance
between the locations in feet. The rate of decrease (i.e., the decrease in concentration per foot) generally
increases toward the east; although the decrease from ST-1 to ST-8 is anomalously steep (Table 4-3).
Table 4-3
Decrease in TCE Concentration per Foot
Location
Separation (feet)
13-Nov-08
15-Dec-08
19-Jan-09
17-Feb-09
16-Mar-09
23-Apr-09
18-May-09
15-Jun-09
15-M-09
ll-Aug-09
15-Sep-09
13-Oct-09
Average
ST-7 - ST-1
13
ST-1 - ST-8
6.7
ST-8 - ST-2
8.75
ST-2 - ST-3
5.7
ST-3 - ST-9
9.7
ST-9 - ST-4
10.25
percent/foot
3.6
0.9
0.7
3.0
1.3
2.7
3.3
4.1
4.9
6.0
3.7
0.8
2.92
7.2
11.3
14.2
10.4
14.7
13.2
10.4
12.5
10.3
18.0
11.9
14.1
12.4
9.1
8.7
8.7
7.8
5.7
8.2
9.4
8.3
8.8
3.4
9.1
13.2
8.37
12.2
10.9
12.5
13.1
12.2
14.3
11.1
14.2
15.2
10.6
12.3
8.0
12.2
11.1
13.4
11.8
13.1
14.2
12.9
13.2
13.3
14.1
13.7
11.6
12.1
12.9
17.0
16.4
16.6
16.7
16.5
16.7
16.7
16.4
17.4
NA
16.7
16.4
16.7
4-2
-------
ST-7
20 07
010
4O
ST-1
2 O
40 .
70
10 O
ST-8
O 2
°4
O 7
O10
ST-2
2O
7O
X O1 0
ST-3
2O«
40
70«
100
MICRO-PURGE
VAPOR PROBES
GROUNDWATER
MONITORING WELL
NESTED MACRO-PURGE
VAPOR PROBES
LEGEND
NESTED MACRO-PURGE VAPOR PROBES
20 MICRO-PURGE VAPOR PROBE WITH DEPTH INDICATED
GROUNDWATER MONITORING WELL
TUBING TYPE CLUSTER
X ABANDONED MICRO-PURGE PROBE
4 IRP GROUNDWATER MONITORING WELL
PAVED AREA
UNPAVED AREA
10'
SCALE
20'
MAS Lemoore-Site 14
U.S. Navy, NAVFAC Southwest, San Diego, California
FIGURE 4-1
SOUTH TRANSECT DETAIL
STREAMS TO 85
Tfc Tetra Tech EM Inc.
-------
It is noteworthy that TCE concentrations measured in well ST-3, which has a 2-foot screen across the
water table, ranged from 22 to 45 (ig/L, while the concentration in well MW14-70A, which has a 15-foot
screen with approximately 12 feet below the water table, was measured at 320 (ig/L in April 2009. Well
ST-3 is located approximately 18 feet north of MW14-70A, and both wells are approximately 4 feet east
of the slab edge (Figure 4-1). TCE concentrations in well MW14-70A have been increasing since June
2001.
A plot of the groundwater TCE concentrations measured over the course of the investigation is presented
in Figure 4-2. The groundwater concentrations were relatively stable for most of the study period, with
concentrations varying by a factor of 3 or less (factor of 2 or less for the higher concentration wells).
However, a spike in concentrations measured in samples collected beneath the concrete slab occurred in
June through August 2009. The reason for this transient increase in concentrations is not clear; however,
it does not appear to be a sampling/analytical artifact, as it was observed in multiple wells, over three
sampling rounds.
Static groundwater levels were measured at each well prior to each sampling event. The groundwater
elevations generally decreased (i.e., depths increased) steadily over the course of the study, which had the
effect of increasing the distance from the groundwater source to the vapor probes (Table 4-4, Figure 4-3).
A modest rise in groundwater levels was observed in February and March 2009, corresponding to the
winter rains received in January through March; however, as groundwater levels were only measured
monthly, direct correlation with specific rainfall events is not possible.
An increase in groundwater elevations was observed in September 2009, at the end of the dry summer
months. The reason for this transient rise in the groundwater table is not known; however, it was likely
related to fire fighter training exercises that are conducted on the aircraft parking area to the north of the
study transect. Runoff water from the training exercises flows from the paved aircraft parking area along
a drainage ditch that runs south between locations ST-4 and ST-5. Percolation of this runoff water may
result in temporarily raised groundwater levels. The wells with the greatest increase in water level from
August to September were ST-4, ST-5, and ST-9 (the closest wells to the drainage ditch), which supports
the conclusion that the September rise in water levels was likely related to fire fighter training exercises.
4.1.3 Soil Gas Samples
4.1.3.1 Macro-Purge Probes
Thirty six macro-purge probes were included in the study. An attempt was made to sample each probe
every month; however, two probes were found to be clogged and were not sampled in November 2008.
The probes were replaced and included in the sampling program starting in December 2008. Over the
course of the study, some additional probes became clogged and could not be sampled. TCE and PCE
were the only compounds measured in soil gas samples. TCE was typically detected at concentrations an
order of magnitude or more higher than the corresponding PCE concentrations in the same sample. Many
samples with measurable TCE concentrations did not contain measurable PCE; therefore, this report
focuses on the TCE data. The complete data set for all months is provided in Appendix E. TCE and PCE
concentrations detected in macro-purge vapor samples in January 2009 are summarized in Table 4-5. The
January 2009 data are representative of the monthly sampling data.
4.1.3.2 Micro-Purge Probes
Micro-purge probes were collocated with the 2-, 4-, 7-, and 10-foot macro-purge probes at locations ST-1
through ST-9 (excluding ST-6). No sub-slab micro-purge probes were installed. Thirty-two micro-purge
probes were included in the November and December sampling rounds. EPA removed the micro-purge
4-4
-------
^ N<* ^
-------
Figure 4-3 Groundwater Levels
Table 4-5
Summary of TCE and PCE Concentrations in Macro-Purge Vapor Samples
January 2009 (ug/m3)
Sample Depth
(ft bgs)
SS
2
4
7
10
SS
2
4
7
10
Vapor Probe Location1
TCE
DL
5.0
5.0
5.0
5.0
5.0
ST-7
4,100
57,000
97,000
130,000
200,000
ST-1
660
9,100
30,000
64,000
84,000
ST-8
290
6,700
23,000
30,000
52,000
ST-2
33
95
1,200
2,600
2,700
ST-3
NA
44
93
230
83
ST-9
NA
ND
20
34
260
ST-4
NA
ND
ND
ND
ND
ST-5
NA
ND
ND
ND
ND
PCE
5.0
5.0
5.0
5.0
5.0
58
1,000
1,700
3,400
4,700
ND
140
450
1,100
1,450
ND
130
340
490
820
ND
ND
42
90
140
NA
ND
ND
39
61
NA
ND
ND
19
44
NA
ND
ND
ND
ND
NA
ND
ND
ND
ND
Notes:
1 - Probe locations arranged from west to east
DL - detection level
ft bgs - feet below ground surface
Hg/m3 - micrograms per cubic meter
NA - not applicable
ND - not detected
PCE - tetrachloroethene
SS - sub-slab
TCE - trichloroethene
4-6
-------
probes at location ST-5 after the December 2008 sampling round and at location ST-4 after the June 2009
sampling round. Therefore, the January through June rounds included only 28 micro-purge probes and
the July through October rounds included only 24 micro-purge probes.
TCE and PCE were the only compounds measured in the micro-purge soil gas samples. Like the macro-
purge samples, TCE was typically measured at concentrations an order of magnitude or more higher than
the corresponding PCE concentrations in the same sample. The complete data set for all months is
provided in Appendix E. TCE and PCE concentrations detected in micro-purge vapor samples in January
2009 are summarized in Table 4-6.
Table 4-6
Summary of TCE and PCE Concentrations in Micro-Purge Vapor Samples
January 2009 (ug/m3)
Sample Depth
(ftbgs)
2
4
7
10
2
4
7
10
Vapor Probe Location1
TCE
DL
5.0
5.0
5.0
5.0
ST-7
32,000
110,000
57,000
78,000
ST-1
2,500
39,000
46,000
66,000
ST-8
1,100
7,600
9,600
12,100
ST-2
170
1,470
1,220
960
ST-3
20
ND
300
250
ST-9
ND
25
27
67
ST-4
ND
ND
ND
ND
PCE
5.0
5.0
5.0
5.0
610
2,900
1,340
2,400
64
640
890
1,400
48
70
160
216
ND
58
56
130
ND
ND
38
46
ND
ND
16
ND
ND
ND
ND
ND
Notes:
1 - Probe locations arranged from west to
DL - detection level
ft bgs - feet below ground surface
Hg/m3 - micrograms per cubic meter
NA - not applicable
east
ND - not detected
PCE - tetrachloroethene
SS - sub-slab
TCE - trichloroethene
A comparison of TCE concentrations detected in macro-purge probes versus the corresponding collocated
micro-purge probe is presented in Table 4-7.
Plots of the macro-purge and micro-purge sample results for TCE are presented in Figures 4-4 and 4-5,
respectively. The plots show that, with the exception of the September 2009 data, the variability in TCE
concentrations was generally limited to less than a factor of 2. A significant spike in concentrations was
observed in the September 2009 data, particularly in the macro-purge samples. This spike in
concentrations is suspected of being related to a possible calibration error (Section 3.3.2.2); therefore, the
September soil vapor data are considered suspect.
4.1.3.3 Sampling Parameters Study
Three parameters were evaluated for the Sampling Parameters Study: purge rate, purge volume, and
sample volume. The experimental approach was to hold two of these parameters constant while varying
the third to assess the impact on measured VOC concentrations. For each of the parameters, five separate
probes were selected and a minimum of five samples were collected from each of the five probes. For the
purge rate experiment, purge volume and sample volume were held at 3 system volumes and 20 mL,
respectively, and purge rate was varied from 100 to 4,000 mL/min. For the purge volume experiment,
4-7
-------
Table 4-7
Comparison of TCE Concentrations in Macro-purge and Micro-purge Vapor Samples
Sampling Round
November 2008
November 2008
November 2008
November 2008
November 2008
November 2008
November 2008
November 2008
November 2008
November 2008
November 2008
November 2008
November 2008
November 2008
November 2008
November 2008
November 2008
November 2008
November 2008
November 2008
December 2008
December 2008
December 2008
December 2008
December 2008
December 2008
December 2008
December 2008
December 2008
December 2008
December 2008
December 2008
December 2008
December 2008
December 2008
December 2008
December 2008
December 2008
December 2008
December 2008
December 2008
January 2009
January 2009
January 2009
January 2009
January 2009
January 2009
January 2009
January 2009
January 2009
January 2009
January 2009
January 2009
January 2009
January 2009
January 2009
Location
ST-1
ST-1
ST-1
ST-1
ST-2
ST-2
ST-2
ST-2
ST-3
ST-3
ST-7
ST-7
ST-7
ST-7
ST-8
ST-8
ST-8
ST-8
ST-9
ST-9
ST-1
ST-1
ST-2
ST-2
ST-2
ST-2
ST-3
ST-3
ST-3
ST-7
ST-7
ST-7
ST-7
ST-8
ST-8
ST-8
ST-8
ST-9
ST-9
ST-9
ST-9
ST-1
ST-1
ST-1
ST-1
ST-2
ST-2
ST-2
ST-2
ST-3
ST-3
ST-3
ST-7
ST-7
ST-7
ST-7
Depth
(feet bgs)
2
4
7
10
2
4
7
10
7
10
2
4
7
10
2
4
7
10
7
10
2
4
2
4
7
10
2
7
10
2
4
7
10
2
4
7
10
2
4
7
10
2
4
7
10
2
4
7
10
2
7
10
2
4
7
10
Macro-purge
Result
8,350
37,600
56,000
90,000
200
1,000
2,700
2,500
197
60
40,000
60,000
92,000
165,000
4,450
8,300
14,700
30,000
44
315
9,800
52,000
71
1,600
4,250
4,200
62
315
93
55,000
130,000
190,000
350,000
7,400
24,500
41,000
55,000
23
34
41
370
9,100
30,000
64,000
84,000
95
1,200
2,600
2,700
44
230
83
57,000
97,000
130,000
200,000
Micro-purge
Result
8,900
64,000
210
38
280
1,900
3,100
1,400
330
300
66,000
158,000
87,000
53,000
6,900
4,100
8,600
7,300
15
35
6,700
38,000
210
1,140
2,700
1,300
22
270
270
30,000
96,000
27,500
114,000
2,400
8,200
9,500
9,400
12
44
28
35
2,500
39,000
46,000
66,000
170
1,470
1,220
960
20
300
250
32,000
110,000
57,000
78,000
Percent
Difference
-6.38%
-51.97%
198.51%
199.83%
-33.33%
-62.07%
-13.79%
56.41%
-50.47%
-133.33%
-49.06%
-89.91%
5.59%
102.75%
-43.17%
67.74%
52.36%
121.72%
98.31%
160.00%
37.58%
31.11%
-98.93%
33.58%
44.60%
105.45%
95.24%
15.38%
-97.52%
58.82%
30.09%
149.43%
101.72%
102.04%
99.69%
124.75%
141.61%
62.86%
-25.64%
37.68%
165.43%
113.79%
-26.09%
32.73%
24.00%
-56.60%
-20.22%
72.25%
95.08%
75.00%
-26.42%
-100.30%
56.18%
-12.56%
78.07%
87.77%
Factor
1.07
1.70
267
2368
1.40
1.90
1.15
1.79
1.68
5.00
1.65
2.63
1.06
3.11
1.55
2.02
1.71
4.11
2.93
9.00
1.46
1.37
2.96
1.40
1.57
3.23
2.82
1.17
2.90
1.83
1.35
6.91
3.07
3.08
2.99
4.32
5.85
1.92
1.29
1.46
10.57
3.64
1.30
1.39
1.27
1.79
1.23
2.13
2.81
2.20
1.30
3.01
1.78
1.13
2.28
2.56
4-8
-------
Table 4-7
Comparison of TCE Concentrations in Macro-purge and Micro-purge Vapor Samples
Sampling Round
January 2009
January 2009
January 2009
January 2009
January 2009
January 2009
January 2009
February 2009
February 2009
February 2009
February 2009
February 2009
February 2009
February 2009
February 2009
February 2009
February 2009
February 2009
February 2009
February 2009
February 2009
February 2009
February 2009
February 2009
February 2009
February 2009
March 2009
March 2009
March 2009
March 2009
March 2009
March 2009
March 2009
March 2009
March 2009
March 2009
March 2009
March 2009
March 2009
March 2009
March 2009
March 2009
March 2009
March 2009
March 2009
April 2009
April 2009
April 2009
April 2009
April 2009
April 2009
April 2009
April 2009
Location
ST-8
ST-8
ST-8
ST-8
ST-9
ST-9
ST-9
ST-1
ST-1
ST-1
ST-1
ST-2
ST-2
ST-2
ST-2
ST-3
ST-3
ST-7
ST-7
ST-7
ST-7
ST-8
ST-8
ST-8
ST-8
ST-9
ST-1
ST-1
ST-1
ST-1
ST-2
ST-2
ST-2
ST-2
ST-3
ST-3
ST-7
ST-7
ST-7
ST-7
ST-8
ST-8
ST-8
ST-8
ST-9
ST-1
ST-1
ST-1
ST-2
ST-2
ST-2
ST-3
ST-3
Depth
(feet bgs)
2
4
7
10
4
7
10
2
4
7
10
2
4
7
10
7
10
2
4
7
10
2
4
7
10
10
2
4
7
10
2
4
7
10
7
10
2
4
7
10
2
4
7
10
10
4
7
10
4
7
10
7
10
Macro-purge
Result
6,700
23,000
30,000
52,000
20
34
260
9,500
22,000
54,000
53,000
186
1,600
2,900
2,840
210
77
44,000
85,000
130,000
150,000
7,700
26,000
27,000
34,000
165
6,547
53,000
65,000
83,000
53
1,200
2,800
3,100
110
38
69,000
130,000
136,000
126,000
12,000
28,000
33,000
34,000
75
53000
74000
76000
1900
3500
3200
290
87
Micro-purge
Result
1,100
7,600
9,600
12,100
25
27
67
3,500
28,500
32,000
44,000
86
1,240
1,500
105
135
98
26,000
110,000
75,000
47,000
2,300
7,100
7,900
11,000
16
2,000
81,000
94,000
130,000
58
1,400
1,900
200
100
110
55,000
200,000
150,000
79,000
3,000
9,300
21,000
20,000
30
72000
83000
51000
1800
2000
1000
140
80
Percent
Difference
143.59%
100.65%
103.03%
124.49%
-22.22%
22.95%
118.04%
92.31%
-25.74%
51.16%
18.56%
73.53%
25.35%
63.64%
185.74%
43.48%
-24.00%
51.43%
-25.64%
53.66%
104.57%
108.00%
114.20%
109.46%
102.22%
164.64%
106.40%
-41.79%
-36.48%
-44.13%
-9.01%
-15.38%
38.30%
175.76%
9.52%
-97.30%
22.58%
-42.42%
-9.79%
45.85%
120.00%
100.27%
44.44%
51.85%
85.71%
-30.40%
-11.46%
39.37%
5.41%
54.55%
104.76%
69.77%
8.38%
Factor
6.09
3.03
3.13
4.30
1.25
1.26
3.88
2.71
1.30
1.69
1.20
2.16
1.29
1.93
27.05
1.56
1.27
1.69
1.29
1.73
3.19
3.35
3.66
3.42
3.09
10.31
3.27
1.53
1.45
1.57
1.09
1.17
1.47
15.50
1.10
2.89
1.25
1.54
1.10
1.59
4.00
3.01
1.57
1.70
2.50
1.36
1.12
1.49
1.06
1.75
3.20
2.07
1.09
4-9
-------
Table 4-7
Comparison of TCE Concentrations in Macro-purge and Micro-purge Vapor Samples
Sampling Round
April 2009
April 2009
April 2009
April 2009
April 2009
April 2009
April 2009
April 2009
April 2009
May 2009
May 2009
May 2009
May 2009
May 2009
May 2009
May 2009
May 2009
May 2009
May 2009
May 2009
May 2009
May 2009
May 2009
May 2009
May 2009
May 2009
June 2009
June 2009
June 2009
June 2009
June 2009
June 2009
June 2009
June 2009
June 2009
June 2009
June 2009
June 2009
June 2009
June 2009
June 2009
June 2009
June 2009
June 2009
June 2009
July 2009
July 2009
July 2009
July 2009
July 2009
July 2009
July 2009
July 2009
July 2009
Location
ST-7
ST-7
ST-7
ST-7
ST-8
ST-8
ST-8
ST-8
ST-9
ST-1
ST-1
ST-2
ST-2
ST-2
ST-3
ST-3
ST-3
ST-7
ST-7
ST-7
ST-7
ST-8
ST-8
ST-8
ST-8
ST-9
ST-1
ST-1
ST-2
ST-2
ST-2
ST-3
ST-3
ST-3
ST-7
ST-7
ST-7
ST-7
ST-8
ST-8
ST-8
ST-8
ST-9
ST-9
ST-9
ST-1
ST-2
ST-2
ST-3
ST-3
ST-3
ST-7
ST-7
ST-7
Depth
(feet bgs)
2
4
7
10
2
4
7
10
10
4
10
4
7
10
2
7
10
2
4
7
10
2
4
7
10
7
7
10
4
7
10
2
7
10
2
4
7
10
2
4
7
10
4
7
10
10
7
10
2
7
10
4
7
10
Macro-purge
Result
110000
212000
210000
210000
17000
39000
38000
41000
110
41000
66000
2500
4000
3400
48
700
280
120000
230000
220000
220000
4700
32000
34000
31000
21
67,000
78,000
1,800
3,100
2,400
130
520
350
100,000
180,000
190,000
170,000
16,000
34,000
33,000
35,000
35
24
260
95,000
5,800
4,000
100
1,100
600
230,000
270,000
300,000
Micro-purge
Result
65000
190000
160000
22000
5000
16000
18000
12000
14
52000
47000
2800
2800
1300
13
300
99
66000
190000
160000
46000
5000
7500
15000
7800
10
27,000
25,000
2,700
1,800
1,100
48
480
290
28,000
82,000
49,000
6,800
4,800
8,500
7,300
2,800
26
19
30
26,000
3,700
2,600
59
960
560
103,000
66,000
20,000
Percent
Difference
51.43%
10.95%
27.03%
162.07%
109.09%
83.64%
71.43%
109.43%
154.84%
-23.66%
33.63%
-11.32%
35.29%
89.36%
114.75%
80.00%
95.51%
58.06%
19.05%
31.58%
130.83%
-6.19%
124.05%
77.55%
119.59%
70.97%
85.11%
102.91%
-40.00%
53.06%
74.29%
92.13%
8.00%
18.75%
112.50%
74.81%
117.99%
184.62%
107.69%
120.00%
127.54%
170.37%
29.51%
23.26%
158.62%
114.05%
44.21%
42.42%
51.57%
13.59%
6.90%
76.28%
121.43%
175.00%
Factor
1.69
1.12
1.31
9.55
3.40
2.44
2.11
3.42
7.86
1.27
1.40
1.12
1.43
2.62
3.69
2.33
2.83
1.82
1.21
1.38
4.78
1.06
4.27
2.27
3.97
2.10
2.48
3.12
1.50
1.72
2.18
2.71
1.08
1.21
3.57
2.20
3.88
25.00
3.33
4.00
4.52
12.50
1.35
1.26
8.67
3.65
1.57
1.54
1.69
1.15
1.07
2.23
4.09
15.00
4-10
-------
Table 4-7
Comparison of TCE Concentrations in Macro-purge and Micro-purge Vapor Samples
Sampling Round
July 2009
July 2009
July 2009
July 2009
July 2009
July 2009
July 2009
August 2009
August 2009
August 2009
August 2009
August 2009
August 2009
August 2009
August 2009
August 2009
August 2009
August 2009
August 2009
August 2009
August 2009
August 2009
September 2009
September 2009
September 2009
September 2009
September 2009
September 2009
September 2009
September 2009
September 2009
September 2009
September 2009
September 2009
October 2009
October 2009
October 2009
October 2009
October 2009
October 2009
October 2009
October 2009
October 2009
October 2009
October 2009
Location
ST-8
ST-8
ST-8
ST-8
ST-9
ST-9
ST-9
ST-2
ST-2
ST-3
ST-3
ST-3
ST-7
ST-7
ST-7
ST-8
ST-8
ST-8
ST-8
ST-9
ST-9
ST-9
ST-2
ST-3
ST-3
ST-7
ST-7
ST-8
ST-8
ST-8
ST-8
ST-9
ST-9
ST-9
ST-2
ST-3
ST-3
ST-7
ST-7
ST-8
ST-8
ST-8
ST-8
ST-9
ST-9
Depth
(feet bgs)
2
4
7
10
4
7
10
7
10
2
7
10
4
7
10
2
4
7
10
4
7
10
10
2
10
7
10
2
4
7
10
4
7
10
10
2
10
7
10
2
4
7
10
7
10
Macro-purge
Result
18,000
48,000
50,000
46,000
47
44
206
4,500
3,900
150
1,030
530
180,000
230,000
220,000
11,000
35,000
42,000
39,000
63
31
290
21,000
430
2,000
710,000
680,000
36,000
110,000
110,000
110,000
120
150
790
5,800
120
1,100
300,000
330,000
19,000
41,000
48,000
51,000
160
360
Micro-purge
Result
15,000
5,000
8,500
7,000
29
25
75*
4,100
1,400
72
1,040
540
77,000
54,000
23,000
11,000
4,000
7,400
4,500
21
44
76
4,300
750
3,000
180,000
120,000
16,000
12,000
32,000
25,000
29
24
150
2,200
150
790
82,000
50,000
7,900
14,000
15,000
12,000
51
100
Minimum:
Maximum:
Percent
Difference
18.18%
162.26%
141.88%
147.17%
47.37%
55.07%
93.24%
9.30%
94.34%
70.27%
-0.97%
-1.87%
80.16%
123.94%
162.14%
0.00%
158.97%
140.08%
158.62%
100.00%
-34.67%
116.94%
132.02%
-54.24%
-40.00%
119.10%
140.00%
76.92%
160.66%
109.86%
125.93%
122.15%
144.83%
136.17%
90.00%
-22.22%
32.80%
114.14%
147.37%
82.53%
98.18%
104.76%
123.81%
103.32%
113.04%
-133.33%
199.83%
Factor
1.20
9.60
5.88
6.57
1.62
1.76
2.75
1.10
2.79
2.08
1.01
1.02
2.34
4.26
9.57
1.00
8.75
5.68
8.67
3.00
1.42
3.82
4.88
1.74
1.50
3.94
5.67
2.25
9.17
3.44
4.40
4.14
6.25
5.27
2.64
1.25
1.39
3.66
6.60
2.41
2.93
3.20
4.25
3.14
3.60
1.00
2368
Definitions:
bgs - below ground surface
TCE - trichloroethene
4-11
-------
1
u
u
800,000
700,000
600,000
5(X),000
400,000
300,000
200,000
100,000
-ST7-SS ^^ST7-2 ^^ST7-4 «^ST7-7
«STl-2 ^^STl-4 ST1-7 ^-STl-iQ
-ST8-4 * STS-7 - ST8-10 ST2-SS
ST2-7 «t ST2-10 -. -ST3-2 ST3-4
ST9-2 ST9-4 ST9-7 ' ST9-10
ST4-7 ST4-10 STS-2 ST5-4
_ .ST7-10 ^^ST1-SS
ST8-SS tr~ STS-2
, . -ST2-2 ST2-4 K
ST3-7 -ST3-10 B%
ST4-2 ST4-4 ll \
ST5-7 STS-1Q 'm~ \
# /*
o^
-------
purge rate and sample volume were held at 200 mL/min and 20 mL, respectively, and purge volume was
varied from 1 to 67 system volumes. For the sample volume experiment, purge rate and volume were
held at 200 mL/min and 3 system volumes, respectively, and sample volume was varied from 10 to 6,000
mL. Tables of results from the sampling parameters study are provided in Appendix B.
4.2 DISCUSSION
4.2.1 Distribution of VOCs in the Subsurface
Figure 4-6 presents a schematic representation of the distribution of TCE along the primary (south)
transect based on the January 2009 macro-purge vapor sample concentrations (corresponding schematic
diagrams based on additional sampling rounds are presented in Appendix F). In viewing these profiles, it
is important to note that the distribution and movement of gas phase VOCs through the vadose zone is
dominated by diffusion processes, which are driven by concentration gradients and not by pressure or
density gradients.
As expected, vapor concentrations decreased with increasing distance from the groundwater source
(Figure 4-6). This observation is consistent with the physical principles of subsurface vapor diffusion
from a groundwater source. Vapor concentrations also decreased horizontally moving out from under the
slab. This observation is consistent with the physical effect of the slab trapping soil vapor and preventing
it from being released to the atmosphere.
TCE concentrations in the top 1 to 2 feet of the groundwater column also decreased moving out from
under the slab. This observation was unexpected based on IRP groundwater sampling data for Site 14.
The TCE concentration in samples from groundwater monitoring well MW14-70A, located off-slab and
immediately south of the vapor sampling transect (Figure 2-3), has been increasing since 2001 and was
measured at 320 (ig/L in April 2009. Thus, TCE concentrations measured along the sampling transect
were expected to be on the order of 300 (ig/L. However, concentrations measured immediately off-slab
(location ST-3) were an order of magnitude lower than the MW14-70A concentrations and decreased to
less than 1 (ig/L at ST-4, approximately 20 feet east of the slab edge (Figure 4-6 and Table 4-2).
The Henry's Law equilibrium vapor concentrations calculated from the measured groundwater
concentrations (assuming a groundwater temperature of 21° C, which is typical of the groundwater
temperatures that were measured during sampling) are in parentheses (Figure 4-6). By comparing the
measured 10-foot bgs vapor concentrations to the calculated equilibrium vapor concentrations, the
calculated equilibrium concentrations were approximately the same as the measured concentrations under
the slab at locations ST-7, ST-1, and ST-8, but were at least an order of magnitude higher than the
measured concentrations from ST-2 through ST-4. This observation indicates that the concentration
gradient across the groundwater-vapor interface was significantly lower beneath the slab than in the
uncovered area. This is likely due to differences in the rate of diffusion in the vapor phase versus the
aqueous phase and the trapping effect of the slab. In the paved area, vapors are trapped at the surface and
must diffuse laterally out from under the slab. This results in higher vapor concentrations throughout the
soil column, with concentrations close to equilibrium at the groundwater-vapor interface. In the
uncovered area, VOCs can quickly diffuse vertically through the vadose zone to the surface and escape to
the atmosphere; thus, VOC mass transfer out of the groundwater and into the soil vapor appears to be the
rate-limiting step. As a result, the vapor concentrations just above the groundwater table in the uncovered
area are relatively low compared to the calculated equilibrium concentrations.
The data presented in Figure 4-6 (and Appendix F) also illustrate how concentration gradients exist at this
site to drive VOC mass from the groundwater source up and out from underneath the slab so that it can
4-13
-------
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VERTICAL EXAGERATION = 5X
6.500 TCE CONCENTRATIONS
IN SOIL VAPOR
FROM MACRO-PURGE
PROBES ((ig/m')
460 TCE CONCENTRATIONS
IN GROUNDWATER ((ig/L)
(240) HENRY'S LAW
EQUILIBRIUM TCE
CONCENTRATION IN SOU
VAPOR (iig/m5)
3
6
9
1 O
1 /
C
;
E
4
« '
' 12
*-"
1
^ Smooth contour (Section 4.2.2)
^ J
069 =- S
) 10 20 30 40 50 60 70 80 90
FEET Jan. 2009
Figure 4-6 Schematic Isoconcentration Contours (January 2009 macro-purge data)
4-14
-------
escape to the atmosphere. Specifically, vertical concentration gradients in the vadose zone drive VOC
mass up from the groundwater source toward the slab or the uncovered ground surface. Horizontal
concentration gradients drive VOC mass in the vapor phase out from under the slab so that it can escape
to the atmosphere. Horizontal gradients also exist in the shallow groundwater to drive VOC mass out
from under the slab; however, it is important to note that the process of diffusive mass transfer occurs
more slowly in the aqueous phase than in the vapor phase. Concentration gradients across the
groundwater-vapor interface drive VOC mass out of the groundwater and into the vapor phase.
Taken together, these observations indicate that the near-slab environment is in a steady state, or dynamic
equilibrium, governed by diffusive mass transfer. Beneath the slab, vapor- and aqueous-phase VOC
concentrations are approximately in equilibrium and the rate limiting step governing mass transfer is the
movement of vapors laterally out from under the slab so that they can escape to the atmosphere. In the
uncovered area, the rate limiting step is the transfer of VOC mass up from deeper groundwater and out of
the groundwater into the vapor phase. Once in the vapor phase, the VOCs diffuse relatively quickly
toward the ground surface. Because the rate of diffusive mass transfer is much slower in the aqueous
phase than in vapor, this process apparently led to depletion of VOCs in the shallow groundwater beneath
the uncovered area. Thus, the presence or absence of a slab may impact VOC concentrations not only in
the vapor phase but also in the shallow groundwater.
4.2.2 Temporal Variability
In general, excluding the September 2009 data (see Section 3.3.2.2), the variability in TCE concentrations
over the 12-month study period was less than a factor of 4 for probes installed under the slab (Figure 4-7).
The variability in concentrations for probes installed in the uncovered areas was higher, generally ranging
from a factor of 4 to approximately 30, but the concentrations in the uncovered areas were lower and thus
subject to more variability (Figure 4-8). Overall, concentrations increased modestly over the study
period.
Comparison of the groundwater concentration data (Figure 4-2) to the vapor measurements (Figures 4-7
and 4-8) indicates that variability in vapor concentrations was not strongly linked to changes in
groundwater concentrations. TCE concentrations in groundwater were relatively stable over the 12 month
study period, with a modest spike observed in July 2009. Soil vapor concentrations also exhibited a
modest spike in July 2009, particularly under the slab. However, a more pronounced spike in vapor
concentrations was observed in the December 2008 data, with no corresponding spike in groundwater
concentrations. The depth to groundwater at each monitoring well increased over the course of the study
(Figure 4-3), which effectively increased the distance between the vapor probes and the groundwater
source of VOCs. This change to the depth of the groundwater would be expected to cause a decrease in
vapor concentrations with time. However, as noted above, the vapor concentrations increased with time,
indicating that factors other than groundwater concentrations and depth to the groundwater source have a
greater effect on variations in the vapor concentrations. The explanation for the steady increase in vapor
concentrations is unclear from the available data; however, the observations that measured groundwater
concentrations beneath the transect remained relatively stable and the depth to groundwater increased
suggests that there may be variability in the soil vapor or groundwater concentrations to the west, or out
of the plane of the study transect, that are affecting transect concentrations. For example, an increase in
vapor concentrations to the west of the transect would likely result in an increase in mass flux toward the
east.
4-15
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TCE in Soil Vapor
Under Slab
Figure 4-7 Temporal Trends in Soil Vapor Concentrations Under the Slab
Figure 4-8 Temporal Trends in Soil Vapor Concentrations in Uncovered Locations
4-16
-------
Review of the schematic isoconcentration contour diagrams presented in Figure 4-6 and Appendix F
indicate that there was no significant seasonal variability in the distribution of TCE in soil vapor; rather,
the diagrams reflect the steady overall increase in concentration with time, as shown more directly in
Figures 4-7 and 4-8. Some subtle variation in the shape of the contours was observed but these are not
believed to be significant.
It should be emphasized that the diagrams presented in Figures 4-6 and 4-9 and Appendix F are schematic
only; therefore, caution is needed in drawing conclusions from the diagrams. Nevertheless, some
observations can be made. Comparison of the contours without vertical exaggeration, as shown for
January 2009 (Figure 4-6) and June 2009 (Figure 4-9), suggests there are two common "shapes" observed
in the contours. The contours for the January data are generally smooth, with lines that steadily steepen
toward the groundwater table. In comparison, the contours for the June data show a stepped shape, with
steep lines in approximately the 3- to 6-foot bgs range, and slightly flatter lines below. Review of all the
profile diagrams in Appendix F suggests that the smooth shaped contours correspond to the wetter months
of January, February, and March, while the stepped contours correspond to drier months of November
and May through August. December and April may be transitional between the two patterns.
The stepped shape indicates that shallow, relatively high concentrations are extending to the east,
effectively creating a shallow zone of anomalously high concentrations relative to the smooth contour
profiles. This suggests that there is a shallow zone of relatively high mass transfer (higher rate of
diffusion) out from under the slab and toward the unpaved area. Nothing was observed in the transect
data that readily explains why there might be this variability in the rate of diffusion, but it is likely a result
of factors outside the plane of the transect. It is also not readily apparent what the relationship to seasons
(i.e., dry versus wet months) might be, particularly considering that the paving extends hundreds or more
feet to the north and west of the sampling transect, which should limit any effects of precipitation on the
underlying soils.
The variability in TCE concentrations measured in micro-purge probes was generally greater than in the
macro-purge probes, and the variability was similar in under-slab probes versus probes from uncovered
areas. Over the 12-month study period, micro-purge concentrations under the slab varied by factors of 3
to 35, while for the probes in the uncovered area the variability ranged from a factor of 2 to 30. It is
suspected that the variability observed in micro-purge samples is in-part due to difficulties in the purging
and sampling process. This is discussed further in Section 4.2.3.
4.2.3 Macro-Purge versus Micro-Purge Sampling
Paired macro-purge and micro-purge soil vapor samples were collected over the course of the 12-month
study. When collecting paired samples, the micro-purge sample was always collected first, followed by
the collocated macro-purge sample. The rationale was that the volume of soil gas removed from the
micro-purge probes was trivial (less than 10 mL) in relation to the volume removed from the macro-purge
probes (-30 to 60 mL); therefore, it was assumed that purging and sampling the micro-purge probes was
unlikely to effect the results obtained from the macro-purge probes, whereas the reverse might not be true.
The percent difference between paired micro-purge and macro-purge samples ranged from 200 to -133
percent and the factors between paired concentrations (i.e., the higher concentration divided by the lower)
ranged from 1 to 2,368 (Table 4-7). However, excluding two outlier results from ST-1 at 7 and 10 feet
bgs in November 2008, the differences ranged from 186 to -133 percent and the factors ranged from 1 to
27. The micro-purge probes at 7 and 10 feet bgs at location ST-1 were found to be damaged in November
2008, and were replaced in December 2008; therefore, it is reasonable to exclude these two outliers from
the November data set.
4-17
-------
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GROUNOWATER (|jg/L)
(240) HENRY'S LAW EQUILIBRIUM
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Figure 4-9 Schematic Isoconcentration Contours (June 2009 macro-purge data)
4-18
-------
To assess the comparability of the two sampling methodologies, the paired results (excluding non-detect
results and the two November 2008 outliers at ST-1 from 7 and 10 feet bgs) were plotted in X-Y space
(Figure 4-10). It can be seen by visual inspection that the correlation between measurement types is poor,
and that generally, the micro-purge probes yielded lower concentrations than the corresponding macro-
purge probes. Statistical analyses were performed to quantitatively evaluate the correlation between the
paired data points and to determine whether sub-dividing the data based on a variety of criteria would
yield a better correlation. The data were evaluated by depth, by location, and by month. Plots of these
sub-divisions of the data set are presented in Appendix G.
sr 300,000
1
IT 250,000
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All depths
150,000
u
E?
50,000
V
Y = 0.337X
r1 = 0.438
150,000 300,000 450,000 600,000
Macro-purge TCE Concentration (ng/m3)
750,000
Figure 4-10 Plot of Micro-Purge versus Macro-Purge TCE Concentrations
Table 4-8 lists the coefficient of determination, the fitted regression coefficients a and b for the linear
regression curve Y = a+bX, and the lower and upper 95% confidence limits for the fitted regression
coefficients a and b. The term X refers to the macro-purge result and Y refers to the micro-purge result.
Table 4-8
Statistical Parameters for Regression Curve Y = a + bX
Depth (feet bgs)
2
4
7
10
All depths
r2
0.784
0.637
0.626
0.533
0.473
Fitted a
923
4,970
8,260
5,680
8,830
Lower a
-2,650
-9,040
-143
-245
4,060
Upper a
4,500
18,900
16,700
11,600
13,600
Fitted b
0.547
0.698
0.310
0.194
0.298
Lower b
0.452
0.532
0.246
0.148
0.254
Upper b
0.643
0.864
0.374
0.239
0.341
Notes:
bgs - below ground surface
r - coefficient of determination
X - macro-purge TCE concentrations
Y - micro-purge TCE concentrations
4-19
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Macro-purge (ng/m3)
Figure 4-11 Plots of Micro-Purge versus Macro-Purge TCE Concentrations by Depth
4-20
-------
It is clear that the r2 of the linear regression models decrease with depth, with the worst correlation
occurring when all of the data are modeled with one expression (Table 4-8, Figure 4-11). Note that the
95% lower confidence limit for coefficient a is negative valued and the 95% upper confidence limit is
positive valued when fitting individual depth division data. This indicates that coefficient a can be zero
valued and; hence, can be eliminated from the regression equation without significant loss of accuracy.
Table 4-9 lists the coefficient of determination, the fitted regression coefficient b for the curve Y = bX
(i.e. a forced to zero), and the lower and upper 95% confidence limits for the fitted regression
coefficient b.
Table 4-9
Statistical Parameters for Regression Curve Y = bX
Depth (feet bgs)
2
4
7
10
All depths
2
r
0.782
0.633
0.600
0.507
0.438
Fitted b
0.561
0.735
0.341
0.215
0.337
Lower b
0.462
0.607
0.263
0.175
0.298
Upper b
0.640
0.863
0.398
0.255
0.376
Notes:
bgs - below ground surface
r2 - coefficient of determination
X - macro-purge TCE concentrations
Y - micro-purge TCE concentrations
A comparison between the r2 of the corresponding Y = a+bX (Table 4-8) and Y = bX (Table 4-9)
regressions clearly indicates that no significant loss of accuracy occurs by dropping coefficient a.
The paired micro-purge and macro-purge probes were installed at the same depths but due to drilling
equipment constraints are separated laterally by approximately 1 foot. Therefore, the differences
observed between paired micro-purge and macro-purge sample results could be attributable in part to
heterogeneities in actual soil gas concentrations over short distances in the subsurface. However, the
consistent low bias in the micro-purge data when compared to the macro-purge suggests other factors are
more important.
It is suspected that a significant portion of the discrepancy between the micro-purge and macro-purge
sample results is due to challenges in sample collection using the micro-purge technique. The very
narrow bore (0.01-inch) of the micro-purge tubing results in significant resistance to flow during purging,
which leads to a vacuum in the sampling train. The vacuum created during sampling may result in
ambient air leaking into the samples which would dilute the TCE and lead to erratic results. This
conclusion is supported by the observation that the comparability between results (i.e. the coefficient of
determination, r2) decreases with increasing depth (Table 4-8, Figure 4-11). The deeper probes have
longer tubing lengths through which the samples must be drawn, and the longer tubing lengths result in
increased resistance to flow, which results in a greater vacuum during sampling and increased probability
of ambient air leaking into the samples.
4-21
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4.2.4 Sampling Parameters Study
The data from the purge rate, purge volume, and sample volume experiments are detailed in Appendix B.
The range in TCE concentrations across the probes used for the sampling parameters study spanned two
orders of magnitude; therefore, two concentration scales (vertical axes) are shown on each of the plots in
Figures 4-12 through 4-14. On each plot, both vertical axes show measured TCE concentrations in
(ig/m3, with the left axis for relatively high concentrations and the right axis for low concentrations.
4.2.4.1 Purge Rate Experiment
Changing the rate of purging from 100 to 4,000 mL/min had little if any effect on the measured TCE
concentrations (Figure 4-12). The probe with the highest concentrations, ST1-7, showed some irregular
variability; however, this was likely due to errors introduced during dilutions. The other four probes
showed no significant change in concentration.
The vacuum induced by purging was monitored for purge rates above 200 mL/min. The maximum
induced vacuum was measured at 6 inches of mercury, which is within the allowable range commonly
cited in guidance documents (e.g., DTSC 2003, ITRC 2007). The silts and clays at NAS Lemoore Site 14
have relatively low permeability (Table 2-2); nevertheless, it is possible that at sites with lower
permeability soils, high purge rates could result in higher induced vacuums which could affect the
measured VOC concentrations. Also, probe construction techniques that do not use sand filter packs,
such as post-run tubing, might also result in higher vacuum at high purge rates because use of a filter pack
increases the surface area of native soils from which vapors can be drawn.
4.2.4.2 Purge Volume Experiment
The measured TCE concentrations generally show a nominal increase in concentrations from 1 to 10
purge volumes; however, the variability is generally within analytical error (Figure 4-13). For one probe,
ST2-7, concentrations decreased from 1 to 3 purge volumes before rising again after 6 and 10 purge
volumes. Overall, purge volume did not appear to have a significant effect on measured TCE
concentrations.
4.2.4.3 Sample Volume Experiment
TCE concentrations showed irregular variability with sample volumes ranging from 10 to 1,000 mL
(Figure 4-14). The only consistent trend observed was that the lowest concentration measured at each
probe was associated with the 6,000 mL sample, suggesting that 6-liter Summa canisters may not be the
best option for soil gas sampling.
4.2.4.4 Summary of Sampling Parameters Study
Overall, the results of this study suggests that purge rate, purge volume, and sample volume have little to
no significant effect on measured VOC concentrations in soil gas samples. The only consistent trend
observed amongst all three experiments was that the 6,000-mL samples consistently yielded the lowest
concentrations from the sample volume experiment.
These findings are consistent with the results from experiments conducted at Vandenberg AFB in a dune
sand environment (EPA 2007). At the Vandenberg site, purge rate and purge volume were also found to
have little to no significant effect on TCE concentrations. Sample volume was also found to have little
significant effect; however, similar to this study, samples collected in 6-liter Summa canisters generally
yielded lower concentrations than smaller volume samples.
4-22
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The results of this study corroborate the similar findings obtained from the study conducted at
Vandenberg AFB (EPA 2007). Together, these studies indicate that for soil types ranging from the highly
permeable dune sands at Vandenberg AFB to the relatively low permeability soils at NAS Lemoore IRP
Site 14, the sampling parameters purge rate and purge volume have no significant effect on measured
VOC concentrations in soil gas samples. The study results further indicate that sample volume has no
significant effect up to approximately 1-liter. However, 6-liter samples consistently yielded somewhat
lower concentrations suggesting that 6-liter Summa canisters may not be appropriate for soil gas
sampling.
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Purge Rate (ml/min)
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4-23
-------
2
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Figure 4-13 Linear Plot of Purge Volume Experiment Data
50,000
5,000
cuo
c
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u
o
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0
0 1,000 2,000 3,000 4,000 5,000 6,000 7,000
Sample Volume (ml)
Figure 4-14 Linear Plot of Sample Volume Experiment Data
4-24
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5.0 CONCLUSIONS
The two primary objectives of this investigation were to: (1) measure the distribution of VOCs in the
vadose zone and shallow groundwater in order to improve understanding of the mechanisms of vapor
migration and intrusion and (2) monitor temporal trends in the VOC distribution over the course of a year.
Secondary objectives included comparison of sampling results obtained from industry standard vapor
probe implants (referred to here as "macro-purge" probes) and a new "micro-purge" methodology, and
assessment of the effect of sampling parameters (i.e., purge rate, purge volume, and sample volume) on
measured soil vapor concentrations. Conclusions relating to each of these objectives are listed under
separate headings below.
Distribution of VOCs in the Vadose Zone and Shallow Groundwater
At the NAS Lemoore study site, the following observations were made with respect to the distribution of
VOCs in the shallow subsurface environment:
Vapor concentrations decrease with increasing distance from the groundwater source and also
decrease moving laterally out from under the slab. Thus, there are vertical and horizontal
concentration gradients that drive VOC mass up toward the slab and the uncovered ground and
also laterally out from under the slab. These observations are consistent with basic physical
principles of diffusive mass-transfer.
Equilibrium concentrations of TCE in soil vapor calculated from the groundwater concentrations
using the Henry's constant were similar to the measured 10-foot bgs vapor concentrations under
the slab, but were approximately an order of magnitude higher than the measured concentrations
in the uncovered area. This indicates that the concentration gradient across the groundwater-
vapor interface is much greater in the uncovered area than under the slab.
TCE concentrations in the top 1 to 2 feet of the groundwater column decrease along the transect
from west to east. The rate of decrease (i.e., the decrease in concentration as a percentage per
foot) generally increases toward the east.
These observations indicate that the near-slab environment is in a steady state, or dynamic equilibrium,
governed by diffusive mass transfer. Beneath the slab, vapor- and aqueous-phase VOC concentrations are
approximately in equilibrium and the rate-limiting step governing mass transfer is the movement of
vapors laterally out from under the slab so that they can escape to the atmosphere. In the uncovered area,
the rate-limiting step is the transfer of VOC mass out of groundwater and into the vapor phase. Once in
the vapor phase, the VOCs diffuse relatively quickly toward the ground surface. Since the rate of
diffusive mass transfer is much slower in the aqueous phase than in vapor, this process may lead to
depletion of VOCs in the shallow groundwater beneath uncovered areas. Thus, the presence or absence
of a slab may impact VOC concentrations not only the vapor phase but also the shallow groundwater.
Further research is warranted to evaluate whether the near-slab vapor profile observed at NAS Lemoore
IRP Site 14 is typical. In particular, an important question is whether a similar vapor profile would
develop at a site with different soil types. At NAS Lemoore IRP Site 14, the vadose zone soils are
primarily low permeability silts and clays. A site with relatively high permeability sandy soils might
develop a different vapor profile due to differences in rates of diffusion in the different soil types as
compared to NAS Lemoore IRP Site 14.
5-1
-------
Temporal Trends in VOC Distribution
Groundwater concentrations were relatively stable throughout the study period varying by a
factor of 3 or less (factor of 2 or less for the higher concentration wells). A modest spike in
groundwater concentrations was observed in the June through August sampling data. Given the
overall weather patterns observed at Lemoore NAS (i.e., relatively cool weather in December
through March with above average rainfall and hot, dry weather for the rest of the year), it does
not appear that the observed spike in concentrations, which occurred in the middle of the dry
summer months, is a seasonal effect.
Soil vapor concentrations under the slab generally varied by a factor of less than 4.
Soil vapor concentrations in the uncovered area were much more variable, with the difference
between the maximum and minimum concentrations varying by a factor of 4 to 30.
Overall, soil vapor TCE concentrations increased during the study period throughout the study
area.
The variability in soil vapor concentrations was not strongly linked to changes in groundwater
concentrations.
Schematic isoconcentration contour profiles, presented in Appendix F, suggest there may be two general
shapes to the contours: smooth contours observed during January through March and stepped contours
observed in May through August. While the profiles are schematic drawings only, they suggest a slightly
different distribution of TCE in the soil vapor during the wet months as compared to the rest of the year.
An explanation for these differences is not readily apparent; however, the shape of the contours suggests
that during the drier months, there is an increased rate of lateral diffusion toward the east in the shallow
(~3 to 6 feet bgs) vadose zone.
Overall, these observations indicate that VOC concentrations under the slab, both in groundwater and soil
vapor, were fairly stable and further sampling rounds would not yield a significant improvement in the
characterization of this site. Vapor concentrations in the uncovered area were more variable and multiple
monitoring rounds may be warranted to fully characterize subsurface conditions there.
Macro-purge versus Micro-Purge
Comparison of the TCE soil vapor concentrations from the micro-purge and macro-purge probes
showed a poor correlation between the two sampling methodologies.
The micro-purge data generally exhibited a low bias relative to the corresponding macro-purge
data.
The discrepancy observed between micro-purge and macro-purge soil vapor concentrations may
in part be due to heterogeneities in in-situ concentrations over short distances, but is likely largely
due to difficulties in obtaining representative samples using the micro-purge probes due to the
very small tubing diameter.
5-2
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Effect of Sampling Parameters on Soil Vapor Concentrations
For a wide range of soil types, from high-permeability dune sands to low permeability silts and
clays, the sampling parameters purge rate and purge volume have no significant effect on
measured VOC concentrations in soil gas samples.
Sample volume has no significant effect up to about 1-liter. However, 6-liter samples yielded
somewhat lower concentrations suggesting that 6-liter Summa canisters may not be appropriate
for soil gas sampling.
5-3
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6.0 RECOMMENDATIONS
This study provides important insights into the behavior of VOCs in the vadose zone and shallow
groundwater, but also raises additional questions. The following are recommendations for further
research.
After 2 years of study, the near slab environment at the NAS Lemoore IRP site 14 is well
characterized. The most pressing question is whether the findings from this site are generally
applicable to other sites or if this site is unique. Similar studies at other sites, particularly sites
with different vadose zone soil types, would shed light on the broad applicability of the findings.
As an interim measure, some insight might be gained by conducting a careful review of existing
data for sites where vapor sampling has been conducted in the near-slab environment.
Discrete depth groundwater sampling at the NAS Lemoore IRP site 14 would provide data on
potential vertical stratification of VOCs in groundwater to support or refute the premise that VOC
mass transfer out of the vadose zone in the uncovered area is affecting shallow groundwater
concentrations.
Further evaluation of the micro-purge sampling technique is warranted to understand the weak
correlation between macro-purge and micro-purge vapor sampling results. As discussed, it is
suspected that the ability to obtain representative samples using the micro-purge technique may
be impacted by the resistance to flow through the 0.01-inch diameter tubing, which has the effect
of creating a vacuum in the sampling train during purging and might lead to leaks of ambient air
into the samples. This issue might be resolved by using tubing with a somewhat larger internal
diameter.
6-1
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7.0 REFERENCES
Abreu and Johnson
2005 Effect of Vapor Source-Building Separation and Building Construction on Soil Vapor
Intrusion as Studied with a Three-Dimensional Numerical Model. Environmental Science and
Technology. Volume 39, No. 12. Pages 4,550-4,561.
California Environmental Protection Agency (Cal/EPA) Department of Toxic Substances Control
(DTSC)
2003 Advisory Active Soil Gas Investigations. January.
Interstate Technology & Regulatory Council (ITRC)
2007 Vapor Intrusion Pathway: A Practical Guideline. January
Tetra Tech EM, Inc. (Tetra Tech)
2008a Quality Assurance Project Plan, for the Investigation of the Vertical Distribution of
VOCs in Soils From Groundwater to the Surface/Subslab. January.
Tetra Tech EM, Inc. (Tetra Tech)
2008b Quality Assurance Project Plan Addendum, for the Investigation of the Vertical
Distribution of VOCs in Soils From Groundwater to the Surface/Subslab. October.
U.S. Environmental Protection Agency (EPA)
2007 Final Project Report for Development of Active Soil Gas Sampling Method. Office of
Research and Development, National Exposure Research Laboratory, Las Vegas, Nevada.
EPA/600/R-07/076.
U.S. Environmental Protection Agency (EPA)
2009 Vertical Distribution of VOCs in Soils from Groundwater to the Surface/Subslab. Office
of Research and Development, National Exposure Research Laboratory, Las Vegas, NV.
EPA/600/R-09/073.
7-1
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Appendix A
Sampling Trip Report
-------
SAMPLING TRIP REPORT
for
Temporal Variation of VOCs in Soils from Groundwater to the
Surface/Subslab
Prepared by:
Tetra Tech EM Inc.
1230 Columbia Street
Suite 1000
San Diego, CA 92101
EPA Contract #EP-C-05-061
Task Order No. 85
February 2010
Prepared for:
Brian A. Schumacher, Task Order Project Officer
National Exposure Research Laboratory
Office of Research and Development
U.S. Environmental Protection Agency
Las Vegas, NV 89114
TETRA TECH
-------
Revision: 0
Date: February 2010
Page: 1
1.0 INTRODUCTION
This Trip Report provides a summary of the sampling activities that were conducted between October 20,
2008 and October 14, 2009 at Naval Air Station (NAS) Lemoore Installation Restoration Program (IRP)
Site 14. The sampling was conducted on behalf of the U.S. Environmental Protection Agency (EPA),
Office of Research and Development, in support of the project titled Temporal Variation ofVOCs in Soils
from Groundwater to the Surface/Sub slab, conducted under EPA Contract Number EP-C-05-061, Task
Order Number 85 (TO 85).
NAS Lemoore is located in the California Central Valley, approximately 40 miles south of Fresno and
180 miles northwest of Los Angeles. IRP Site 14 is located in the operations area of NAS Lemoore and
consists of maintenance buildings, hangars, and aircraft parking areas (Figure 1).
The primary contracted project field team included environmental consultants from Tetra Tech (John
Felts, Matt Houlahan, Joachim Eberharter, and James Elliot) and H&P Mobile Geochemistry (Blayne
Hartman, Tom Scherbart, Janis Villarreal, Kurt Schindler, and Amilcar Sanchez). In addition to
contractor personnel, the project field team included the EPA Task Order Project Officer (Brian
Schumacher) and EPA scientist (John Zimmerman). Mr. Frank Nielson, from the NAS Lemoore IRP
office, provided logistical support and was often on-site.
The field investigation for TO 85 was completed over 13 mobilizations. Geophysical clearance for
groundwater monitoring well and additional soil vapor probe locations was conducted on October 20,
2008 by Precision Locating. Concrete coring for monitoring wells and probe locations on the concrete
slab was conducted on October 20, 2008 by Penhall Company (Penhall). Drilling and groundwater
monitoring well installation was conducted on October 21 and 22 by H&P Mobile Geochemistry
(HPMG). Soil gas probes were installed by HPMG at new locations ST-7, ST-8, and ST-9, on October
22. Monthly groundwater and soil vapor sampling was conducted over the next 12 months from
November 12, 2008 through October 14, 2009.
2.0 GROUNDWATER WELL AND VAPOR PROBE INSTALLATION
Soil vapor probe installation, soil sampling, and groundwater well installation was conducted in
accordance with the procedures detailed in the QAPP (Tetra Tech 2008a, c).
On October 21, 2008, groundwater monitoring wells were installed at locations ST-1, ST-4, ST-5, ST-7,
and ST-9, and on October 22 groundwater wells were installed at locations ST-2, ST-3, and ST-8 (Figure
2, Table 1). Also on October 22, soil vapor probes were installed at 2, 4, 7, and 10 feet bgs at locations
ST-7, ST-8, and ST-9 and subslab at locations ST-7 and ST-8. Soil samples were collected from 2, 4, 7,
and 10 feet bgs at locations ST-7, ST-8, and ST-9.
For this investigation, groundwater monitoring wells were installed immediately adjacent to vapor probe
locations ST-1 through ST-5 and ST-7 through ST-9. The wells were installed in boreholes drilled
approximately 2 feet below the water table using a direct-push drill rig. Groundwater was encountered at
a depth of approximately 12 to 13 feet bgs at each location. The wells were constructed using 0.75-inch
diameter polyvinylchloride (PVC) well casing and screen. The screen and casing was placed in the open
borehole so that approximately 1 foot of well screen was above the water table and 2 feet were below.
Clean #2/12 sand was then poured down the annular space to form a filter pack to approximately 1 foot
above the well screen. The wells were sealed to the surface with hydrated bentonite and completed at the
surface in flush-mount, traffic rated well boxes. The relatively short (i.e. 3 feet long) well screens were
used in order to obtain groundwater samples that are representative of the conditions near the top of the
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UNPAVED AREA
FORMER UNPAVED AREA
LANDSCAPED AREA
TCE PLUME A ZONE- JANUARY 2007
Sar\\ **
Francisco O
INDUSTRIAL WASTEWATER LINE
STORM DRAIN
OPERATIONS
AREA
Lemoore ^
FORMER S
NAS LEMOORE BOUNDAR
5000' 0 5000' 10000
III I
SCALE: 1" = 10000'
AIRCRAFT PARKING
STUDY AREA
FORMER
ANHOLE
WASH
RACK
50' 0 50' 100'
*
SCALE: 1" = 100'
NAS Lemoore-Sitel 4
U.S. Navy, NAVFAC Southwest, San Diego, California
FIGURE 1
DETAILED SITE MAP
STREAMS TO 85
WASH
RACK
(ft Tetra Tech EM Inc
?
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LEGEND
A5 SOIL VAPOR PROBE LOCATION (NOT USED FOR THIS STUDY)
ST^ SOIL VAPOR PROBE WITH COLLOCATED GROUNDWATER WELL
^- EXISTING GROUNDWATER WELL
X FENCE LINE
UNPAVED AREA
SECONDARY
TRANSECT
NT-6
A
ST-6
A
PRIMARY
TRANSECT
NASLemoore-Site14
U.S. Navy, NAVFAC Southwest, San Diego, California
FIGURE 2
SOIL VAPOR PROBE AND
GROUNDWATER WELL TRANSECTS
STREAMS TO 85
Tetra Tech EM Inc.
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water column, at the groundwater-vadose zone interface. The monitoring wells were identified by the
location ID appended with "MW" to indicate a monitoring well.
Table 1
Groundwater Sample Summary
Location
ST-1
ST-2
ST-3
ST-4
ST-5
ST-7
ST-8
ST-9
Well ID
ST1-MW
ST2-MW
ST3-MW
ST4-MW
ST5-MW
ST7-MW
ST8-MW
ST9-MW
Total Depth
(feet bgs)
14.0
13.5
13.7
12.8
12.6
14.2
14.1
13.3
Installation
Date
10/21/08
10/22/08
10/22/08
10/21/08
10/21/08
10/21/08
10/22/08
10/21/08
The vapor probes were installed in pilot holes advanced to 10 feet bgs using a direct push rig. Soils
encountered in the pilot holes consisted primarily of silty sands, clayey sands, and clays. Soil samples
were collected at the vapor probe depths of 2, 4, 7, and 10 feet bgs in each of the three pilot holes drilled
on October 22 (ST-7 through ST-9).
Soil vapor probes were constructed as follows. Approximately 3 inches of #2/12 sand was poured into
the bottom of the pilot holes. A 1-inch long gas-permeable probe tip attached to 1/8-inch diameter
Nylaflow tubing was then lowered through the drill rod to the top of the sand. Additional sand was
poured around the sampling probe until it extended approximately 2 inches above the probe to form an
approximately 6-inch long sand pack around the sample point. Approximately 12 inches of dry bentonite
was then placed on top of the sand pack, followed by hydrated bentonite to approximately 3 inches below
the next sampling depth (i.e. 7 feet bgs). This process was repeated to install four nested soil vapor
probes in each pilot hole, at depths of 2, 4, 7, and 10 feet bgs. At locations on the concrete pad, the
subslab vapor probes were installed in the same way, but in a separate, 1-inch diameter hole that was
drilled through the concrete with an electric hammer drill. The sampling probes were completed at the
surface with approximately 18 inches of Nylaflow tubing extending out of the ground and a luer valve
fitted to the end of the tubing. A schematic diagram of the probe installations is provided in Figure 3.
The individual probes were identified by the location ID and the depth separated by a dash (e.g., the probe
installed at 4 feet bgs at location ST-1 is designated ST1-4). The subslab probes were identified with the
location ID and "SS" (e.g. ST1-SS). Table 2 provides a summary of the probe installation details.
Concurrently with the installation of the above vapor probes, which are referred to as "macro-purge"
vapor probes, EPA installed "micro-purge" vapor probes. Micro-purge vapor probes were collocated
with the macro-purge vapor wells at locations ST-1 through ST-4, and ST-7 through ST-9 at depths of 2,
4, 7, and 10 feet bgs. Subslab micro-purge vapor wells were not installed. The micro-purge vapor probes
consisted of 0.01-inch inner diameter (ID) stainless steel tubing epoxied into steel point holders. The
stainless steel tubing was threaded through the drill-rods, which were driven to the target sampling depth
using the EPA-operated direct-push rig. Upon reaching the target depth, the drill rod was pulled up
approximately 1 inch to expose the drop-off point to the vadose zone. The drill rods were left in place
during sampling in order to seal out ambient air; thus micro-purge probes at multiple depths were
installed in separate boreholes, rather than being nested in a single boring.
-------
1/8-INCH OD
NYLAFLOW TUBING
2-WAY
LUER VALVE
T
SURF
B
0
'ACE
X
I
^ f
.c ^
c
:;
!i
: _ :'
'.'.
^\
SWAGELOK^. ^CONCRETE
FITTING \ /
/ ' /
/ 7 /
/ 7 /
/ 7 /
/ 7 /
/ 7 /
/ 7 /
/ 7 /
/ 7 /
/ 7 /
/ 7 /
/ 7 /
||
_ ;> o j
.'.:.'.:'.
II
'n'ci'. -S
II
.^? i
?=.'.' z ^ ^°_ ^^
:':--' ^-HYDRATED G
9 BENTONITE
TA° rrr?MrAr)i r ' '*
oAo rCKI ICAdLC ^v.
PROBE TIP ^^CLEAN SAND
PACK
SUB-SLAB
PROBE
PA° ^^^^/l^A^l r
bAo rLKrILADLL
PROBE TIP
-« HYDRATED
GRANULAR
BENTONITE
* DRY GRANULAR
BENTONITE
-* CLEAN SAND
PACK
NOT TO SC/
MAS Lemoore-Sit
U.S. Navy, NAVFAC Southwest, S
FIGURES
NESTED SOIL-GAS PROBES
SOIL VAPOR PROBE
CONSTRUCTION SCHEMATIC
STREAMS TO 85
Tetra Tech EM Inc.
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6
A summary of the probe installation details is provided in Table 2, along with the geographic coordinates
for each location. It was determined in July 2009 that a malfunction in the GPS receiver had resulted in
incorrect coordinates being reported for probe locations ST-1 through ST-6 and NT-1 and NT-6 in the TO
65 Trip Report (Tetra Tech 2008b); therefore, Table 2 below includes the corrected coordinates for all
probes installed under the STREAMS program atNAS Lemoore.
Table 2
Soil Vapor Probe Installation Details and Coordinates
Location
ID
ST-1
ST-2
ST-3
ST-4
ST-5
ST-6
ST-7
Macro
Probe ID
ST1-SS
ST1-2
ST1-4
ST1-7
ST1-10
ST2-SS
ST2-2
ST2-4
ST2-7
ST2-10
ST3-2
ST3-4
ST3-7
ST3-10
ST4-2
ST4-4
ST4-7
ST4-10
ST5-2
ST5-4
ST5-7
ST5-10
ST6-2
ST6-4
ST6-7
ST6-10
ST7-SS
ST7-2
ST7-4
ST7-7
ST7-10
Installation Date
February 11,2008
February 11,2008
January 18, 2008
January 22, 2008
January 22, 2008
January 18, 2008
October 22, 2008
Probe
Depth
(feet bgs)
Sub-Slab
2
4
7
10
Sub-Slab
2
4
7
10
2
4
7
10
2
4
7
10
2
4
7
10
2
4
7
10
Sub-Slab
2
4
7
10
Coordinates
(Easting)
6283734.19
6283748.25
6283753.98
6283771.04
6283789.04
6283807.32
6283723.72
Coordinates
(Northing)
2002852.99
2002859.41
2002860.26
2002870.24
2002878.29
2002885.52
2002848.69
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7
Table 2 (cont.)
Location
ID
ST-8
ST-9
NT-1
NT-2
NT-3
NT-4
NT-5
NT-6
Macro
Probe ID
ST8-SS
ST8-2
ST8-4
ST8-7
ST8-10
ST9-2
ST9-4
ST9-7
ST9-10
NT1-SS
NT 1-2
NT 1-4
NT 1-7
NT1-10
NT2-SS
NT2-2
NT2-4
NT2-7
NT2-10
NTS -2
NTS -4
NTS -7
NT3-10
NT4-2
NT4-4
NT4-7
NT4-10
NT5-2
NT5-4
NT5-7
NT5-10
NT6-2
NT6-4
NT6-7
NT6-10
Installation Date
October 22, 2008
October 22, 2008
February 12, 2008
February 12, 2008
January 22, 2008
January 18, 2008
February 12, 2008
February 12, 2008
Probe
Depth
(feet bgs)
Sub-Slab
2
4
7
10
2
4
7
10
Sub-Slab
2
4
7
10
Sub-Slab
2
4
7
10
2
4
7
10
2
4
7
10
2
4
7
10
2
4
7
10
Coordinates
(Easting)
6283739.86
6283761.65
6283718.98
6283733.55
6283736.84
6283757.85
6283773.38
6283791.38
Coordinates
(Northing)
2002857.26
2002866.30
2002883.21
2002890.65
2002892.46
2002902.04
2002910.10
2002917.53
Notes:
bgs below ground surface
3.0
SOIL GAS AND GROUND WATER SAMPLING AND ANALYSES
Once installation was completed in October 2008, monthly groundwater and soil gas sampling began in
November 2008 and was finished in October 2009. Groundwater sampling was conducted by purging
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each well dry, from least contaminated to most contaminated, and allowing the well to recharge with
groundwater. During the first two rounds of sampling, equilibrium purging of the groundwater wells was
attempted; however, the recharge rate was too slow and the wells consistently purged dry. While purging,
groundwater temperature, electrical conductivity, pH, dissolved oxygen, and oxidation reduction potential
were measured using YSI instrument and turbidity was measured using a Hach Turbidity meter.
Groundwater samples were collected using disposable polyethylene bailers and submitted to the HPMG
fixed laboratory in Carlsbad, California for volatile organic compound (VOC) analysis via EPA method
SW8260B. Unless otherwise specified every groundwater well was sampled during each monthly round
in the following order ST5-MW, ST4-MW, ST9-MW, ST3-MW, ST2-MW, ST8-MW, ST1-MW, and
ST7-MW.
Soil gas samples were analyzed in an on-site mobile laboratory operated by HPMG. Macro-purge soil
gas probes were purged using disposable 60-ml polypropylene syringes attached to 3-way luer valves and
samples were collected in glass syringes after purging. Three system volumes were purged from each
macro-purge probe followed by collection of a 20-ml sample. System volumes for macro-purge probes
were calculated as 6, 11, 17, 26, and 35 ml.
Micro-purge soil gas probes were purged and sampled using glass syringes provided by EPA. Three system
volumes were purged from each micro-purge probe followed by collection of a 2.5-ml sample. System
volumes for the micro purge probes were estimated to be 2.0, 2.1, 2.1, and 2.2 ml for the 2-, 4-, 7-, and 10-
foot deep probes, respectively. Dilution was used at location ST-7, ST-1, and ST-8 due to high
concentrations. Unless otherwise specified every micro-purge and macro-purge probe was sampled during
each monthly round.
3.1 November 2008 Sampling Round
The week of November 12, 2008 marked the first round of sampling of the new groundwater monitoring
wells and soil gas probes. After arriving on site the team setup on location ST-5 to begin purging each of
the groundwater wells. A peristaltic pump was used to purge the wells. Specific tubing lengths were cut
for each well depending on their total depth. These well-specific tubing lengths were used each month to
purge the wells.
On November 12 wells ST5-MW, ST4-MW, ST9-MW, and ST3-MW were purged dry. Due to the
limited volume of water in each well, only a single YSI and turbidity meter reading could be recorded for
each well. After all the wells had been purged dry they were allowed to recharge and then sampled. At
the end of the day Blayne Hartman arrived on site to set up the mobile laboratory and gas chromatograph
(GC).
On November 13, groundwater wells ST1-MW, ST2-MW, ST7-MW, and ST8-MW were purged dry and
sampled upon recharge. Vapor sampling was started in the afternoon after the GC instrument was set up
and calibrated. Macro-purge soil gas sampling was completed for all probes except ST1-SS, ST2-SS, and
ST3-2. These probes were plugged and needed to be reinstalled.
On November 14, micro-purge vapor samples were collected from all locations and the plugged probes
identified the previous day were reinstalled. The stainless steel tubing in micro-purge probe ST1-MP-7
was found to be loose and in need of replacement. By the end of the day, all the macro-purge and micro-
purge soil vapor probes had been sampled.
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3.2 December 2008 Sampling Round
On December 15, 2008 each of the groundwater monitoring wells were purged dry and sampled following
the procedures outlined at the beginning of this section. One YSI and turbidity reading was recorded for
each location.
Vapor sampling began on December 16 at location ST-7, but was quickly halted due to rain. Vapor
sampling was completed on December 17. The following micro-purge probes developed a vacuum
during purging: ST7-MP-10, ST5-MP-4, ST5-MP-7, ST4-MP-7, and ST4-MP-10. These probes were
successfully sampled by using an extremely slow purge rate. Micro-purge probes ST1-MP-7 and
ST-MP-10 were not sampled because the stainless steel tubing was found to be loose and the probes
needed to be replaced.
Penhall was mobilized to the site to core additional holes in the concrete slab so that the loose micro-
purge probes could be replaced and to provide additional core holes for future probe installations. Penhall
cored three holes at ST-1, one hole at ST-8, and one hole at ST-2.
Following completion of the regular monthly sampling round, the auto-sampler system was set up and
launched. Table 3 lists the probes that were incorporated into the auto-sampler system.
Table 3
Auto-sampler Configuration
Auto-
sampler
Port
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
Soil Gas
Probe
CalGas
ST8-SS
ST8-2
ST8-4
ST8-7
Outside air
ST3-7
ST3-4
ST3-2
ST9-7
ST9-4
ST9-2
ST2-SS
ST2-2
ST2-4
ST2-7
Notes
Outside air after January 20
On December 22 and 23, EPA removed the micro-purge probes at ST-5 and replaced probes ST1-MP-7
and ST1-MP-10
3.3 January 2009 Sampling Round
On January 19, 2009 each of the groundwater monitoring wells were purged dry and sampled following
the procedure outlined at the beginning of this section. One YSI and turbidity reading was recorded for
each well. By the end of the day, each of the groundwater wells was sampled, progressing from the least
to the most contaminated.
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The following day, January 20, vapor probe sampling was performed at all locations. The sub-slab probe
at ST-2 was found to be clogged, so it was replaced with a new probe installed adjacent to the original.
In early January, the auto-sampler was malfunctioning due to a problem with the purge pump and due to
water being drawn into the system from probe ST8-2. After the regular sampling round was completed,
the purge pump was replaced and probe ST8-2 was disconnected from the system (Table 3). In addition,
the new ST2-SS probe was incorporated in the auto-sampler at Port 13.
3.4 February 2009 Sampling Round
On February 17, 2009 each of the groundwater monitoring wells were purged dry and sampled following
the procedure outlined at the beginning of this section. One YSI and turbidity reading were recorded for
each location.
The auto-sampler was shut off on the morning of February 18 and the regular monthly vapor sampling
was conducted. All of the probes were successfully sampled. After completion of the monthly sampling
round, the auto-sampler was restarted.
3.5 March 2009 Sampling Round
On March 16, 2009 each of the groundwater monitoring wells were purged dry and sampled following the
procedure outlined at the beginning of this section. One YSI and turbidity reading were recorded for each
location.
The auto-auto sampler was shut off and the regular monthly vapor sampling was started on March 17.
The probes at locations ST-5, ST-4, ST-9, ST-3, ST-2, and ST-8 at all depths were sampled. The
remaining soil vapor probes were sampled on March 18. It was determined that micro-purge probe ST7-
MP-10 had a loose fitting septa that needed to be replaced.
3.6 April 2009 Sampling Round
Vapor probe sampling was conducted on April 22. A slight vacuum was noticed at ST3-MP-4 as well as
ST8-2. Micro-purge probe ST1-MP-2 was found to be clogged and water was observed in the syringe
during purging; therefore, this probe was not sampled. In addition, macro-purge probe ST2-2 was found
to be clogged and no sample was taken.
Groundwater samples were collected on April 23. Each of the groundwater monitoring wells was purged
dry and sampled following the procedure outlined at the beginning of this section. One YSI and turbidity
reading was recorded for each well.
3.7 May 2009 Sampling Round
On May 18, 2009 each of the groundwater monitoring wells were purged dry and sampled following the
procedure outlined at the beginning of this section. One YSI and turbidity reading was recorded for each
well. The regular monthly vapor sampling round was also conducted on May 18. During vapor probe
sampling it was noted that there were strong vacuums in probes ST2-MP-7, ST8-2, and ST1-4, and that
probes ST1-2, ST2-2, ST1-MP-2, and ST1-MP-7 were all clogged.
During May 19 and 20, experiments were conducted to evaluate the effect of purge rate, purge volume,
and sample volume on soil vapor results. The experiments were conducted similarly to the experiments
conducted at Vandenberg AFB under STREAMS TO 05 (EPA 2007).
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3.8 June 2009 Sampling Round
On June 15, 2009 each of the groundwater monitoring wells were purged dry and sampled following the
procedure outlined at the beginning of this section. One YSI and turbidity reading was recorded for each
well.
Vapor sampling was conducted on June 16. During vapor sampling it was noted that probes ST1-2,
ST1-4, ST2-2, and ST3-MP-4 were clogged, and that ST1-MP-2 still draws water. With the exception of
these five probes, all of the vapor probes were successfully sampled.
Geophysical utility clearance for the equilibration study scheduled for July was conducted on June 17.
Doug Young from Precision Locating conducted the work and cleared four separate proposed locations
for the study. The four locations were on the unpaved ground, immediately adjacent to the concrete slab.
The locations were marked with spray paint so that they could be easily identified in July.
3.9 July 2009 Sampling Round
During the week of July 13, 2009, groundwater and vapor sampling was completed as usual and a study
of probe equilibration time was conducted under STREAMS TO-65. The equilibration study consisted of
installing several new locations of nested macro-purge and micro-purge soil gas probes and sampling the
probes periodically until the measured TCE concentrations stabilized. The purpose of the study was to
determine the time required for newly installed soil gas probes to stabilize. The study lasted the whole
week and ran in conjunction with the regularly scheduled groundwater monitoring well and soil vapor
probe sampling.
The equilibration study consisted of intensive sampling of the newly installed probes over the first three
days (July 13 through 15), which resulted in the GC instrument being operating at capacity; therefore,
only equilibration study samples were collected and analyzed during this time period.
By July 16, the rate of sampling necessary for the equilibration study had decreased and so the regular
monthly vapor sampling round was conducted. A number of probes were found to be clogged during the
July round: ST1-2, ST1-4, ST1-7, ST2-2, ST2-4, ST5-4, ST7-2, and ST1-MP-2. In addition, EPA
removed the micro-purge probes at location ST-4; therefore, starting with the July round, no micro-purge
samples were collected from this location.
The following day, July 17, each of the groundwater monitoring wells was purged dry and sampled
following the procedure outlined at the beginning of this section. One YSI and turbidity reading was
recorded for each location.
The equilibrium study was concluded at the end of the day on July 17.
3.10 August 2009 Sampling Round
On August 11, 2009 each of the groundwater monitoring wells were purged dry and sampled following
the procedure outlined at the beginning of this section. One YSI and turbidity reading were recorded for
each location. After purging, ST4-GW and ST5-GW did not recharge with enough water to allow
sampling. These two wells were allowed to recharge through the following day and still did not contain
sufficient water; therefore, no groundwater samples were collected from ST4-GW and ST5-GW during
the August round.
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Vapor sampling was conducted on August 12. Macro-purge probes ST1-2, ST1-4, ST1-7, ST1-10,
ST2-2, ST2-4, ST4-2, ST4-4, ST5-4, ST7-SS, and ST7-2 and micro-purge probes ST1-MP-2 and
ST3-MP-4 were found to be clogged and were not sampled. All of the other probes were successfully
sampled.
3.11 September 2009 Sampling Round
On September 15, 2009 each of the groundwater monitoring wells were purged dry and sampled
following the procedure outlined at the beginning of this section. One YSI and turbidity reading were
recorded for each location. Vapor sampling was also started on September 15 while waiting for the
groundwater wells to recharge.
Vapor sampling was completed on September 16. Macro-purge probes ST1-2, ST1-4, ST1-7, ST1-10,
ST2-2, ST2-4, ST2-7, ST3-4, ST3-7, ST7-SS, ST7-2, and ST7-4 and micro-purge probes ST1-MP-2 and
ST3-MP-4 were found to be clogged and were not sampled. Probes ST4-2, ST4-4, and ST5-4, which
were clogged during the August sampling round were found to purge adequately in September and were
sampled.
3.12 October 2009 Sampling Round
On October 13, 2009 each of the groundwater monitoring wells were purged dry and sampled following
the procedure outlined at the beginning of this section. One YSI and turbidity reading were recorded for
each location.
Soil gas sampling was conducted on October 14. Macro-purge probes ST1-2, ST1-4, ST1-7, ST1-10,
ST2-2, ST2-4, ST2-7, ST3-4, ST3-7, ST4-2, ST4-7, ST5-4, ST5-7, ST7-SS, ST7-2, ST7-4, and ST8-SS
and micro-purge probes ST1-MP-2, ST3-MP-4, and ST9-MP-4 were found to be clogged and were not
sampled. All of the other probes were successfully sampled.
4.0 FIELD QUALITY CONTROL
A sub-set of the soil vapor sampling probes were leak checked during the TO 65 investigation by placing
a cloth rag in a plastic bag, saturating the rag with 1,1-difluoroethane (DFA), placing the bag over the
surface completion of the probe, and then purging the probe normally and collecting a sample. None of
the probes failed the leak test; since all probes were installed using the same procedures, it was assumed
that all probes were sufficiently sealed.
Field duplicate vapor samples were collected to measure the reproducibility and precision of the total
sampling system. Field duplicate samples were collected at a rate of approximately 9 percent. Of the 67
field duplicate vapor samples collected during the program, only seven exceeded the Quality Assurance
Project Plan (QAPP) (Tetra Tech 2008a, c) specified criterion of ±40 relative percent difference (RPD).
A total of 94 groundwater samples plus 10 duplicates were collected over the 12 sampling rounds. All of
the RPD results for the duplicates were within the QAPP specified criterion of ±40 RPD.
One field duplicate soil sample was analyzed for the set of 12 field samples analyzed. The only analyte
detected in the soil samples was TCE. The RPD between the primary and duplicate sample TCE
concentrations was 22, well within the QAPP criterion of ±40.
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5.0 HEALTH AND SAFETY
Each field team member was required to sign a form acknowledging they had received and understood the
site-specific health and safety plan. Each day of field work began with a Tailgate Health and Safety
meeting followed by equipment checking and preparation. The daily health and safety meetings were
conducted by the Tetra Tech site supervisor and covered site-specific health and safety concerns including
physical, chemical, and biological hazards.
There were no accidents or other health and safety incidents during the field program.
6.0 REFERENCES
Tetra Tech EM, Inc. (Tetra Tech)
2008a Quality Assurance Project Plan, for the Investigation of the Vertical Distribution of
VOCs in Soils From Groundwater to the Surface/Subslab. January.
Tetra Tech EM, Inc. (Tetra Tech)
2008b Sampling Trip Report, Vertical Distribution of VOCs in Soils from Ground Water to the
Surface/Subslab. May
Tetra Tech EM, Inc. (Tetra Tech)
2008c Quality Assurance Project Plan Addendum, for the Investigation of the Vertical
Distribution of VOCs in Soils From Groundwater to the Surface/Subslab. October.
U.S. Environmental Protection Agency (EPA). 2007. Final Project Report for the Development of an
Active Soil Gas Sampling Method. Office of Research and Development, National Exposure
Research Laboratory, Las Vegas, NV. EPA/600/R-07/076.
-------
Appendix B
Purging Parameters Study
-------
APPENDIX B
Evaluation of the Effect of Sampling Parameters on VOC
Concentrations in Soil Vapor Samples
Prepared by:
Tetra Tech EM Inc.
1230 Columbia Street
Suite 1000
San Diego, CA 92101
EPA Contract #EP-C-05-061
Task Order No. 85
July 2010
Prepared for:
Dr. Brian A. Schumacher, Task Order Project Officer
National Exposure Research Laboratory
Office of Research and Development
U.S. Environmental Protection Agency
Las Vegas, NV 89119
«»EPA fib
TETRA TECH
-------
CONTENTS
Section Page
1.0 INTRODUCTION B-l
2.0 METHODOLOGY B-l
3.0 RESULTS AND DISCUSSION B-2
4.0 SUMMARY B-3
5.0 CONCLUSION B-3
6.0 REFERENCES B-9
Figures
B-l Detailed Site Map, IRP Site 14, NAS Lemoore, California B-7
B-2 Groundwater Contours, A Zone, January 2007 B-7
B-3 Trichloroethene Plume in the A Zone Aquifer, January 2007 B-8
Tables
B-l Macro-Purge Soil Gas Probe Installation Details B-2
B-2 Purge Rate Experiment Sample Summary B-4
B-3 Purge Volume Experiment Sample Summary B-5
B-4 Sample Volume Experiment Sample Summary B-6
B-i
-------
1.0 INTRODUCTION
In May 2009, Tetra Tech conducted experiments to evaluate the effect of purge rate, purge volume, and
sample volume (referred to here as the principal parameters) on measured volatile organic compound
(VOC) concentrations in soil gas samples. Similar experiments were conducted in October 2006 at
Installation Restoration Program (IRP) Site 15 on Vandenberg Air Force Base (AFB). The results of the
Vandenberg AFB study are reported in Final Project Report for Development of Active Soil Gas
Sampling Method (U.S. EPA 2007). The vadose zone at the Vandenberg AFB study site consisted of
homogeneous, highly permeable dune sands. The objective of the study at NAS Lemoore IRP Site 14
was to repeat the experiments in relatively heterogeneous and low permeability silts and clays to evaluate
whether soil type would affect the findings.
2.0 METHODOLOGY
The experiments were conducted using a sub-set of the existing, south transect, macro-purge soil vapor
probes. Probes were selected to provide a range of baseline trichloroethene (TCE) concentrations (i.e. the
concentrations previously measured at a given probe) and a range of probe depths (i.e. tubing lengths).
The probes used for this study were constructed in the same way as those used for the Vandenberg AFB
study with the exception that at NAS Lemoore the Nylaflow tubing used was 1/8-inch diameter, while at
Vandenberg AFB 1/4-inch tubing was used.
The overall approach was to collect multiple samples from the same vapor probe while varying one of the
principal parameters and holding the others at a constant setting, referred to as the baseline setting. The
baseline settings were chosen to be consistent with the experiments conducted at Vandenberg AFB and
industry standard sampling procedures. The baseline principal parameter settings were as follows:
Purge Rate: 200 milliliters per minute (ml/min)
Purge Volume: 3 system volumes
Sample Volume: 20 milliliters (ml)
A system volume was considered the volume of the 1/8-inch Nylaflow tubing plus the volume of the
probe. The tubing volume was estimated as 1 ml per foot of tubing. Calculated system volumes for each
probe are shown in Table B-l.
The principal parameter settings were varied as follows:
Purge Rate: 100 milliliters to 4,000 ml/min
Purge Volume: 1 to 67 system volumes
Sample Volume: 10 to 6,000 ml
For purge rates of 200 ml/minute or less, probes were purged using a 60-ml syringe equipped with a
three-way valve. For purge rates of 500 ml/min and higher, a portable electric pump was used. Samples
up to 60-ml were collected in glass syringes. Samples greater than 60 and up to 1,000 ml were collected
in Tedlar bags. The 6,000-ml samples were collected in 6-liter Summa canisters.
B-l
-------
Table B-l
Macro-Purge Soil Gas Probe Installation Details
Location
ID
ST-1
ST-2
ST-3
ST-8
ST-9
Probe ID
ST1-7
ST2-4
ST2-7
ST2-10
ST3-2
ST3-4
ST3-7
ST3-10
ST8-4
ST8-7
ST8-10
ST9-10
Installation Date
February 11,2008
February 11,2008
January 18, 2008
October 22, 2008
October 22, 2008
Easting
6283734.19
6283748.25
6283753.98
6283739.86
6283761.65
Northing
2002852.99
2002859.41
2002860.26
2002857.26
2002866.30
Probe
Depth
(feet bgs)
7
4
7
10
2
4
7
10
4
7
10
10
Length of
Sandpack
(inches)
6
6
6
6
6
6
6
6
6
6
6
6
System
Volume
(ml)
9
6
9
12
4
6
9
12
6
9
12
12
Definitions:
bgs - below ground surface
ml - milliliters
All of the samples were analyzed on-site in the H&P Mobile Geochemistry (HPMG) laboratory using
EPA method SW8021. The analyses were performed following EPA method 8000 protocols, modified
for soil gas. The instrument used was an SRI 8610 gas chromatograph equipped with a photoionization
detector (PID) and an electron capture detector (ECD). The detection level was 5 micrograms per cubic
meter (ug/m3). Samples collected in glass syringes were directly injected into the analytical instrument.
Samples collected in Tedlar bags and Summa canisters were sub-sampled with a syringe and injected.
3.0 RESULTS AND DISCUSSION
The experimental data for the purge rate, purge volume, and sample volume experiments are summarized
on Tables B-2, B-3, and B-4 respectively, and linear plots are presented on Figures B-l, B-2, and B-3. As
shown on the tables, there was a two order of magnitude range in TCE concentrations across the probes;
therefore, two concentrations scales (vertical axes) are shown on each of the plots in Figures B-l through
B-3. On each plot, both vertical axes show measured TCE concentrations in ug/m3, with the left axis for
relatively high concentrations and the right axis for low concentrations.
Purge Rate Experiment
The TCE concentrations observed during the purge rate experiment are summarized in Table B-2 and
linear plots of the purge rate experiment data are shown in Figure B-l. It is clear from these data
presentations that purge rate had little if any effect on the measured TCE concentrations. The probe with
the highest concentrations, ST1-7, showed some irregular variability; however, this was likely due to
errors introduced during dilutions. The other four probes showed no significant change in concentration.
The vacuum induced by purging was monitored for purge rates above 200 ml/min (Table B-2). The
maximum induced vacuum was 6 inches of mercury, which is within the allowable range commonly cited
in guidance (e.g., DTSC 2003, ITRC 2007). At other sites with lower permeability soils, it is possible
that high purge rates could result in higher induced vacuums, which could affect the resulting measured
VOC concentrations.
B-2
-------
Purge Volume Experiment
The TCE concentrations observed during the purge volume experiment are summarized in Table B-3 and
linear plots of the purge volume experiment data are shown in Figure B-2. The measured TCE
concentrations generally show a nominal increase in concentrations from 1 to 10 purge volumes;
however, the variability is generally within analytical error. Furthermore, for one probe (ST2-7),
concentrations decreased from 1 to 3 purge volumes before rising again after 6 and 10 purge volumes.
Overall, purge volume did not appear to have a significant effect on measured TCE concentrations.
Sample Volume Experiment
The TCE concentrations observed during the sample volume experiment are summarized in Table B-4
and linear plots of the sample volume experiment data are shown in Figure B-3. TCE concentrations
showed irregular variability with sample volumes ranging from 10 to 1,000 ml. The only consistent trend
observed was that the lowest concentration measured at each probe was associated with the 6,000 ml
sample, suggesting that 6-liter Summa canisters may not be the best option for soil gas sampling.
4.0 SUMMARY
Overall, the results of this study suggests that purge rate, purge volume, and sample volume have little to
no significant effect on measured VOC concentrations in soil gas samples. The only consistent trend
observed amongst all three experiments was that the 6,000-ml samples consistently yielded the lowest
concentrations.
These findings are consistent with the results from the experiments conducted at Vandenberg AFB in a
dune sand environment (EPA 2007). At the Vandenberg site, purge rate and purge volume were also
found to have little to no significant effect on TCE concentrations. Sample volume was also found to
have little significant effect; however, similarly to this study, samples collected in 6-liter Summa canisters
generally yielded lower concentrations than smaller volume samples.
5.0 CONCLUSION
The results of this study corroborate the similar findings obtained from the study conducted at
Vandenberg AFB. Together, these studies indicate that For soil types ranging from the highly permeable
dune sands at Vandenberg AFB to the relatively low permeability soils at NAS Lemoore Site 14,, the
sampling parameters purge rate and purge volume have no significant effect on measured VOC
concentrations in soil gas samples. The study results further indicate that sample volume has no
significant effect up to approximately 1-liter; however, 6-liter samples consistently yielded somewhat
lower concentrations, suggesting that 6-liter Summa canisters may not be appropriate for soil gas
sampling.
B-3
-------
Table B-2
Purge Rate Experiment Sample Summary
Location
ST3-4
ST1-7
ST2-10
ST3-7
ST8-7
Definitions
inHg
(Hg/m3)
ml/min
NA
%RSD
StDev
Sample ID
ST3-4-PR100
ST3-4-PR200
ST3-4-PR500
ST3-4-PR1000
ST3-4-PR2000
ST3-4-PR4000
ST3-4-PR4000
ST1-7-PR100
ST1-7-PR200
ST1-7-PR500
ST1-7-PR1000
ST1-7-PR2000
ST1-7-PR4000
ST1-7-PR4000
ST2-10-PR100
ST2-10-PR200
ST2-10-PR500
ST2-10-PR1000
ST2-10-PR2000
ST2-10-PR4000
ST3-7-PR100
ST3-7-PR200
ST3-7-PR500
ST3-7-PR1000
ST3-7-PR2000
ST3-7-PR4000
ST8-7-PR100
ST8-7-PR200
ST8-7-PR500
ST8-7-PR1000
ST8-7-PR2000
ST8-7-PR4000
- inches of mercury
Purge Rate
(ml/min)
100
200
500
1000
2000
4000
4000
100
200
500
1000
2000
4000
4000
100
200
500
1000
2000
4000
100
200
500
1000
2000
4000
100
200
500
1000
2000
4000
Sample
Time
13:47
14:12
14:42
15:15
15:39
16:29
16:33
Average
StDev
%RSD
14:02
14:24
15:02
15:33
16:01
16:55
16:59
Average
StDev
%RSD
13:43
14:08
14:53
15:23
15:51
16:45
Average
StDev
%RSD
13:51
14:16
14:48
15:19
15:44
16:41
Average
StDev
%RSD
13:57
14:20
14:57
15:27
15:57
16:49
Average
StDev
%RSD
TCE Vacuum
((ig/m ) (inHg) Purge Method Notes
250
250
230
200
200
180
117
218
26.7
12.2%
56000
60000
48000
57000
53000
59000
53000
55143
3833.3
7.0%
3500
3500
3400
3400
3400
3400
3433
47.1
1.4%
780
750
760
750
750
770
760
11.5
1.5%
27000
28000
28000
27000
28000
29000
27833
687.2
2.5%
Notes:
NA
NA
1
1
1.5
2.5
2.5
NA
NA
1
2
3.5
5.5
5.5
NA
NA
1
2
3
6
NA
NA
1
1.5
2
4
NA
NA
1
1.5
2.5
2
Syringe
Syringe
Syringe
Pump
Pump
Pump 10 second purge
Pump 90 second purge
Syringe
Syringe
Syringe
Pump
Pump
Pump 10 second purge
Pump 90 second purge
Syringe
Syringe
Syringe
Pump
Pump
Pump
Pump
Syringe
Syringe
Syringe
Pump
Pump
Pump
Syringe
Syringe
Syringe
Pump
Pump
Pump
Purge volume was set at 3 system volumes
- micrograms per cubic meter
- milliliters per minute
- not applicable
Sample volume was set at 20 ml
Samples collected
19 May 2009
- percent relative standard deviation
- standard deviation
B-4
-------
Table B-3
Purge Volume Experiment Sample Summary
Location
ST1-7
ST2-7
ST2-4
ST8-10
ST9-10
Definitions
inHg
(ug/m3)
ml/min
%RSD
StDev
Sample ID
ST1-7-PV1
ST1-7-PV2
ST1-7-PV3
ST1-7-PV6
ST1-7-PV10
ST1-7-PV67
ST2-7-PV1
ST2-7-PV2
ST2-7-PV3
ST2-7-PV6
ST2-7-PV10
ST2-7-PV67
ST2-4-PV1
ST2-4-PV2
ST2-4-PV3
ST2-4-PV6
ST2-4-PV10
ST2-4-PV67
ST8-10-PV1
ST8-10-PV2
ST8-10-PV3
ST8-10-PV6
ST8-10-PV10
ST8-10-PV67
ST9-10-PV1
ST9-10-PV2
ST9-10-PV3
ST9-10-PV6
ST9-10-PV10
ST9-10-PV67
Purge Volume Purge Volume Sample TCE
(system volumes) (ml) Time (ug/m j Notes
1
2
3
6
10
67
1
2
3
6
10
67
1
2
3
6
10
67
1
2
3
6
10
67
1
2
3
6
10
67
8
16
24
48
80
500
8
16
24
48
80
500
5
10
15
30
50
500
11
22
33
66
110
500
11
22
33
66
110
500
10:08
10:13
10:19
10:23
10:28
10:43
Average
StDev
%RSD
10:51
10:57
11:02
11:06
11:10
11:15
Average
StDev
%RSD
11:37
11:42
11:46
11:50
11:55
11:59
Average
StDev
%RSD
12:12
12:17
12:23
12:27
12:32
12:36
Average
StDev
%RSD
12:55
13:01
13:07
13:15
13:19
13:23
Average
StDev
%RSD
57000
68000
67000
72000
67000
73000
67333
5185
7.7%
5300
4800
4600
4800
5000
4500
4833
262
5.4%
2300
2400
2500
2600
2700
2700
2533
149
5.9%
Exceeded calibration range
26000
Exceeded calibration range
29000
27000
27000
27250
1090
4.0%
430
460
860 Suspected carryover
520
500
370
523
158
30.2%
Notes:
- inches of mercury
- micrograms per cubic meter
- milliliters per minute
- percent relative standard deviation
- standard deviation
Purge rate was set at 200 ml/min
Sample volume was set at 20 ml
Samples collected 19 May 2009
B-5
-------
Table B-4
Sample Volume Experiment Sample Summary
Sample Volume
Location
ST3-2
ST3-10
ST2-4
ST2-7
ST8-4
Definitions
inHg
(ug/m3)
ml/min
%RSD
StDev
Sample ID
ST3-2-SV10
ST3-2-SV60
ST3-2-SV500
ST3-2-SV1000
ST3-2-SV6000
ST3-10-SV10
ST3-10-SV60
ST3-10-SV500
ST3-10-SV1000
ST3-10-SV6000
ST2-4-SV10
ST2-4-SV60
ST2-4-SV500
ST2-4-SV1000
ST2-4-SV6000
ST2-7-SV10
ST2-7-SV60
ST2-7-SV500
ST2-7-SV1000
ST2-7-SV6000
ST8-4-SV10
ST8-4-SV60
ST8-4-SV500
ST8-4-SV1000
ST8-4-SV6000
- inches of mercury
(ml)
10
60
500
1000
6000
10
60
500
1000
6000
10
60
500
1000
6000
10
60
500
1000
6000
10
60
500
1000
6000
TCE
Sample Time (ug/m3) Sample Container
8:57
9:23
10:37
11:01
12:53
Average
StDev
%RSD
9:02
9:58
10:42
11:06
12:36
Average
StDev
%RSD
9:07
10:02
10:46
11:11
13:02
Average
StDev
%RSD
9:11
10:07
10:51
11:16
13:08
Average
StDev
%RSD
9:17
10:14
10:56
11:21
13:16
Average
StDev
%RSD
Notes:
130
150
140
190
130
148
22
15.0%
320
380
420
530
230
376
100
26.6%
2600
2800
2600
2700
2300
2600
167
6.4%
4100
4300
4100
4200
3700
4080
204
5.0%
41000
38000
36000
37000
33000
37000
2608
7.0%
Syringe
Syringe
Tedlar bag
Tedlar bag
Summa
Syringe
Syringe
Tedlar bag
Tedlar bag
Summa
Syringe
Syringe
Tedlar bag
Tedlar bag
Summa
Syringe
Syringe
Tedlar bag
Tedlar bag
Summa
Syringe
Syringe
Tedlar bag
Tedlar bag
Summa
Purge rate was set at 200 ml/min
- micrograms per cubic meter
- milliliters per minute
Purge volume was set
at 3 system volumes
Sampls collected 20 May 2009
- percent relative standard deviation
- standard deviation
B-6
-------
7n nnn -,
-
jqn nnn
p>
c cr\ nnn
0)
c 4n nnn
tt
i_
c 30 000 :
0
o
O on nnn
LU
o :
H-i n nnn
-
0_
C
--ST1-7 if ST8-7 * ST3-4 *-ST2-10 ST3-7
|
< Scale
^^
X*-^-+ H "A
< Scale
) 1,000 2,000 3,000 4,000 5,0
Purge Rate (ml/min)
7 nnn
:
6 nnn
<>
c nnn ^
at
3.
A nnn S
^P
: 3 000 "c
0
0
c
o nnn .Q
LU
: o
1 nnn I
-
00
Figure B-l Linear Plot of Purge Rate Experiment Data
on nnn -,
P>
Eyn nnn
~u\
^~ Gr\ nnn
' DU.UUU
C :
o
'43 ^n nnn
2 :
+-
Q 4U,UUU
O :
c
Oon nnn
LU :
20,000 -
1- :
i n nnn
0"
C
^
/ ^^cyo jg
< Scale -B-ST2-7
* ST9-10
1_ _
*^ Scale -=>
-^**~->^^^ ^^^^^^if'
*£- Scale
Suspected carryover
I 20 40 60 8
Purge Volume (system volumes)
m nnn
1 9,000
: 8,000 ^
- 7,000
- c
o
- 6,000 '^
: (0
,uuu =
:
-------
0 1,000 2,000 3,000 4,000 5,000 6,000 7,000
Sample Volume (ml)
Figure B-3 Linear Plot of Sample Volume Experiment Data
-------
6.0 REFERENCES
California Environmental Protection Agency (Cal/EPA) Department of Toxic Substances Control
(DTSC)
2003 Advisory Active Soil Gas Investigations. January.
Interstate Technology & Regulatory Council (ITRC)
2007 Vapor Intrusion Pathway: A Practical Guideline. January
U.S. Environmental Protection Agency (EPA)
2007 Final Project Report for Development of Active Soil Gas Sampling Method. Office of
Research and Development, National Exposure Research Laboratory, Las Vegas, Nevada.
EPA/600/R-07/076.
B-9
-------
Appendix C
Example Chromatograms and Laboratory Data
-------
Calibration files for ECD/PID for Lemoore 12/17/2008
TCE
cone (ppbv) area area/cone
PID
ECD
1000
200
100
cone (ppbv)
100
50
25
129
25
13.4
%RSD=
area
2257
1444
857
0.129
0.125
0.134
2.80%
area/cone
22.6
28.9
34.3
PCE
area area/cone
105 0.105
21.5 0.108
13.3 0.133
%RSD= 11.00%
area area/cone
7681 76.8
5581 112
3304 132
%RSD= 16.70%
%RSD= 21.40%
-------
Lab name: H&P
Client: TETRATECH
Client ID: TO-85
Analysis date: 12/17/200811:15:27
Method: Syringe Injection
Lab ID: TT121608-T2
Description: CHANNEL 1 - PID
Data file: 121608P-59.CHR {)
Sample: 100PPBV
Operator: Hartman
-0.800 8.000
- ~ '
- - . - - - - -/0.583
" . - -- = = -= -/0.833
- --- -TCE/1.316
i rz'"="": ---PCE/2.233
< > :, "~ I
3- :
i
4r \
Component Retention Area External Internal Units
0.066 29.1260 0,0000 0.0000
0.583 27.9640 0.0000 0.0000
0.833 32.4800 0.0000 0.0000
TCE 1.316 13.4400 128.4895 706.6922 ug/m3
PCE 2.233 13.3020 151.8493 1050.7973 ug/m3
116.3120 280.3388 1757.4894
-------
Lab name:
Client:
Client ID:
Analysis date:
Method:
Lab ID:
Description:
Data file:
Sample:
Operator:
H&P
TETRA TECH
JO-85
12/17/200811:35:49
Syringe Injection
TT121608-T2
CHANNEL 1 - PID
121608P-63.CHRQ
200 PPBV
Hartman
-1.600
16.000
-70.683
-70.850
- - -71.100
TCE/1.583
PCE/2.483
Component Retention Area External Internal
TCE
PCE
0,683
0.850
1.100
1.583
2.483
11.1160 0.0000
25.6140 0.0000
56.0150 0.0000
24,9620 238.6424
21.5300 245,7763
Units
0.0000
0.0000
0.0000
1312.5335 ug/m3
1700.7717 ug/m3
139.2370 484.4187 3013.3052
-------
Lab name:
Client:
Client ID:
Analysis dale:
Method:
Lab ID:
Description:
Data file:
Sample:
Operator:
H&P
TETRA TECH
TO-85
12/17/200811:29:57
Syringe Injection
TT121608-T2
CHANNEL 1 - PID
121608P-62.CHRQ
1000PPBV
Hartman
-6,400
64.000
3
-/0.850
- -/1.100
- TCE/1.583
PCE/2,500
Component Retention Area External Internal
Units
TCE
PCE
0.850
1.100
1.583
2.500
19.7670
279.8510
128.6300
105.3280
0.0000
0.0000
1229.7323
1202.3744
0.0000
0.0000
6763.5277 ug/m3
8320.4311 ug/m3
533.5760 2432.1067 15083.9588
-------
Lab name:
Client:
Client ID:
Analysis date:
Method:
Lab ID:
Description:
Data file:
Sample:
Operator:
H8.P
tetra Tech
TO-85
12/17/200814:01:41
SYRINGE
TT1216Q8-T2
CHANNEL 2 -ECD
121608E-86.CHR0
25 PPBV
Hartman
-204.800
2048.000
- air/1.133
- TCA/1.700
TCE/1.966
~1_~^-" '= - =~ PCE/2.900
Component Retention Area External Internal
air
TCA
TCE
PCE
1.133
1.700
1.966
2.900
8396.9700
1162.5500
856.6880
3304.5260
0.0000
0,0000
29.2952
29.4049
Units
0.0000
0.0000
161.1234 ug/m3
203.4821 ug/m3
13720.7340 58.7001 364.6055
-------
Lab name: H&P
Client: tetra Tech
Client ID: TO-85
Analysis date: 12/17/2008 14:06:06
Method. SYRINGE
Lab ID: TT121608-T2
Description: CHANNEL 2 - ECD
Data file: 121608E-87.CHR ()
Sample: 50 PPBV
Operator: Hartman
-204,800 2048,000
i~/o.iso
- air/1.133
TCA/1.700
TCE/1.966
- PCE/2,900
41-
Component Retention Area External Internal Units
0.150 44.5790 0.0000 0.0000
air 1.133 8207,7100 0.0000 0,0000
TCA 1.700 2303.5140 0.0000 0.0000
TCE 1.966 1444.1330 49.3833 271.6083 ug/m3
PCE 2.900 5581.1400 49.6631 343.6687 ug/m3
17581.0760 99.0464 615.2770
-------
Lab name:
Client:
Client ID:
Analysis date:
Method:
Lab ID:
Description:
Data file:
Sample:
Operator:
H&P
tetra Tech
TO-85
12/17/2008 14:10:06
SYRINGE
TT121608-T2
CHANNEL 2 -ECD
121608E-88.CHRQ
100 PPBV
Hartman
-204.800
3-
2048.000
=..=..., ._- air/1.133
- TCA/1.716
- TCE/1.966
=- =- PCE/2.916
Component Retention Area External Internal
air
TCA
TCE
PCE
1,133
1.716
1.966
2.916
8065.8460
3081.1660
2257.8260
7681.5670
0.0000
0.0000
77.2082
68.3535
Units
0.0000
0.0000
424.6453 ug/m3
473.0063 ug/m3
21086.4050 145.5617 897.6515
-------
Lab name: H&P
Client: tetraTech
Client ID: TO-85
Analysis date: 12/17/200811:29:58
Method: SYRINGE
Lab ID: TT121608-T2
Description: CHANNEL 2 - ECD
Data file: 121608E-62.CHR ()
Sample: 1000 ppbv
Operator: Hartman
-204.800 _ _ _ 2048X300
.:. --.. - - ----. - ... : air/1.116
-/1.416
- TCA/1.716
- TCE/1.966
- PCE/2.916
Component Retention Area External Internal Units
air 1.116 5477.5520 0.0000 0.0000
1.416 126.8180 0.0000 0.0000
TCA 1716 6713.4590 0.0000 0.0000
TCE 1.966 5607.3240 398.9558 2194.2570 ug/m3
PCE 2.916 15647.9480 207.3262 1434.6976 ug/m3
33573.1010 606.2821 3628.9546
-------
Lab name: H&P
Client: TETRATECH
Client ID: Streams TO
Analysis date: 11/14/2008 12:51:12
Description: CHANNEL 1 - PID
Data file: PiD-111408-40,CHR()
Sample: ST2MP-7
Operator: Hartman
-/0.616
-/1.433
' ~ : i: _- . -= - ' -- TCE/1.733
PCE/2.833
Component Retention Area External Internal Units
TCE 1.733 9.5150 566.3690 3115.0298 ug/m3
PCE 2.833 0.6840 19.7688 136.8000 ug/m3
10.1990 586.1378 3251.8298
-------
Lab name: H&PT3
Client: Tetra tech
Client ID: Streams TO
Analysis date: 11/14/200812:51:12
Description: CHANNEL 2 - BCD
Data file: ECD-11140840.CHR ()
Sample: ST2MP-7
Operator: Hartman
VO.OOO
-/0.850
-n.116
... -...- .-.air/I ,366-'
TCA/1,883
'.; " - . . - - - -TCE/2.266
PCE/3.166
Component Retention Area External Internal Units
air 1.366 29691,1440 0.0000 0,0000
TCA 1.883 2361,7620 0.0000 0.0000
TCE 2,266 16744.5910 201.9773 1110.8751 ug/m3
PCE 3.166 6376.8300 42.6444 295.0992 ug/m3
55174.3270 244.6217 1405.9744
-------
Lab name: H&P
Client: TETRATECH
Client ID: TO-85
Analysis date: 01/20/200916:29:22
Method: Syringe Injection
Lab ID: TT121608-T2
Description: CHANNEL 1 - PID
Data file: Q12009P-67.chr ()
Sample: ST1-21
Operator. Hartman
, .. .. ..... .. . ...... . .. 64.000
I
-/0516
"'----/1.083
" " . ~ ....... ::~ . " ..... - ..... - --- TCE/1.833
PCE/3.000
Component Retention Area External Internal Units
TCE 1.833 141.4420 1661.5800 9138.6902 ug/m3
PCE 3.000 2.2910 26.9134 186.2405 ug/m3
143.7330 1688.4934 9324.9306
-------
Lab name:
Client:
Client ID:
Analysis date:
Method:
Lab ID:
Description:
Data file:
Sample:
Operator:
H&P
tetra Tech
TO-85
01/20/2009 16:29:22
SYRINGE
TT121608-T2
CHANNEL 2 - ECD
012009E-67.CHR()
ST1-21
Hartman
-204.800
2048.000
air/1250
TCA/1.816
- TCE/2,283
PCE/3.383
Component Retention Area
air
TCA
TCE
PCE
1.250
1.816
2.283
3.383
External Internal
Units
13445.7610
229.8160
12286.8700
3424,1050
0.0000
0.0000
537.1395
20,5627
0.0000
0.0000
2954.2674 ug/m3
142.2941 ug/m3
29386.5520 557.7022 3096.5614
-------
Lab name. H&P
Client: TETRATECH
Client ID: TO-85
Analysis date: 03/17/2009 13:40:04
Method: Syringe Injection
Lab ID: TT121608-T2
Description: CHANNEL 1 - PID
Data file: 031709P-44.CHR ()
Sample: ST2-4 DUP
Operator: Russ
-1.600 _ _ ^laoog
! -/0.566
1 ' ' -/0.950
; ; ." --- - TCE/1.816
3^
Component Retention Area External Internal Units
TCE 1.816 24,4200 226.5306 1245,9184 ug/m3
24.4200 226.5306 1245.9184
-------
Lab name:
Client:
Client ID:
Analysis date:
Method:
Lab ID:
Description:
Data file:
Sample:
Operator:
H&P
tetra Tech
TO-85
03/17/200913:40:04
SYRINGE
TT121608-T2
CHANNEL 2 -ECD
031709E-44.CHRO
ST2-4 DUP
Russ
-204,800
i- -/0.016 - --
2048.000
41...
air/1233
1 TCA/1.750
- TCE/2.133
PCE/3.083
Component Retention Area
air
TCA
TCE
PCE
1.233
1.750
2.133
3.083
External Internal
6162.9730
99.9280
1719.4700
379.9850
0.0000
0.0000
62.8275
3.2956
Units
0,0000
0.0000
345.5511 ug/m3
22.8057 ug/m3
8362.3560 66.1231 368.3568
-------
Lab name: H&P
Client: tetra Tech
Analysis date: 04/22/2009 14:34:06
Method: SYRINGE
Lab ID: TT121608-T2
Description: CHANNEL 2 - ECD
Data file: 0422ECDa40.chr (C:/PEAK329/042209)
Sample: s13mp-1Q
Operator: JV
-60.000
-/0.150
-/0.583
-/2.S66
200.000
"air/1.216'
- TCE/2,083
PCE/3.033
Component Retention Area External Internal
Units
air
TCE
PCE
1,216 10400.8080 0.0000
2.083 439.5200 14.5711
3.033 430.6570 2.8351
11270.9850 17.4062
0.0000
80.1409 ug/m3
19.6191 ug/m3
99.7600
-------
Lab name: H&P
Client: TETRATECH
Analysis date: 04/22/2009 14:34:06
Method: Syringe Injection
Lab ID: TT121608-T2
Description: CHANNEL 1 - PID
Data file. 0422PIDa40.CHR (C:/PEAK329/042209)
Sample: st3mp-10
Operator: JV
-0.625
-/0066
..... '...' '-- -/1.033
-/1 616
TCE/1.800
2 h
; '"'-/2.316
-72.566
.^.'.-' PCE/2.900
' -/3.350
Component Retention Area External Internal Units
TCE 1.800 3.5740 33.1540 182.3469 ug/m3
PCE 2.900 2.8180 25.3874 175.6807 ug/m3
6.3920 58.5414 358.0277
-------
Lab name: H&P
Client: tetra Tech
Analysis date: 06/16/200912:39:07
Method: SYRINGE
Lab ID: TT121608-T2
Description: CHANNEL 2 - ECD
Data file: Q616ECD-46.CHR (C:/)
Sample: ST3-2'
Operator: ts
-102.400
-/0.133
1024.000
1-
-: =airtL20Q.;
- TCE/2.033
3L
PCE/2.933
Component Retention Area External Internal
air
TCE
PCE
Units
1.200 18063.7700 0.0000
2.033 871.8420 23.3567
2.933 530.5000 2.5603
0.0000
128.4620 ug/m3
17.7175 ug/m3
19466.1120 25.9171 146.1794
-------
Lab name: H&P
Client: TETRATECH
Analysis date: 06/16/200912:39:07
Method: Syringe Injection
Lab ID: TT121608-T2
Description: CHANNEL 1 - PID
Data file: 061609PID-46.chr(C:/}
Sample: ST3-2'
Operator: TS
-2.000
................... -T-/0.033-
: 'TCE/1.800
2r /'-/1.983
i I
,' Unknown/2.516
3T i-13.066
\ 1 -/3.S66
4!-
Component Retention Area External Internal Units
TCE 1.800 2.1360 13.7540 75.6471 ug/m3
Unknown 2.516 0.5820 0,0000 0.0000
2.7180 13.7540 75.6471
-------
Lab name: H&P
Client: TETRATECH
Analysis date: 08/12/200912:58:13
Method: Syringe Injection
Lab I'D: TT121608-T2
Description: CHANNEL 1 - PID
Data file: C:\Peak329\0812PID-46.CHR ()
Sample: ST8-MP-21
Operator: T.S.
QC batch:
-2.100
; -/0.283
lf\ COO
,J ./0.700
! ,' -/2.366
I
31 ' . PCE/2.933
15.400
-/1.033
-TGE/1.783;
5L
Component Retention Area External Internal
TCE
PCE
Units
1.783 90,5390 402.4403 2213.4215 ug/m3 / 5
2.933 2,4400 10.7953 10.7953 ppbv
92.9790 413.2355 2224.2168
-------
Lab name:
Client;
Analysis date:
Method:
Lab ID:
Description:
Data file:
Sample:
Operator:
QC batch:
H&P
tetra Tech
08/12/200912:58:13
SYRINGE
TT121608-T2
CHANNEL 2 -ECD
0812ECD-46.chr()
ST8-MP-21
T.S,
0
-409.600
-/0.116
,1-/!800
/1.666
air/1.216
TCE/2.033
4096.000
3h
PCB2.900
5h
Component Retention Area
air
TCE
PCE
External Internal
Units
1.216 18095.0450 558.3167
2.033 11045.6780 389.2755
2.900 4379,2220 16.1197
558.3167
21410151 ug/m3
111.5482 ug/m3
- 555
33519.9450 963.7119 2810.8800
-------
Lab name: H£P
Client: TETRATECH
Analysis date: 10/14/2009 11:27:50
Method: Syringe Injection
Lab ID: TT121608-T2
Description: CHANNEL 1 - PID
Data file: C:\Peak329\1014PID-26.CHR ()
Sample: ST3-MP-10'
Operator: T,S,
QC batch:
-2.100
-/0.616
:r:= -/0.900
15.400
2L /- - f "
i /-/2.3161
TCE/1.800
PCE/3.016
Component Retention Area External Internal
Units
TCE
PCE
1.800 22.8000 143.2836 788.0597 ug/m3
3.016 3.9540 21.7133 21.7133 ppbv
26.7540 164,9969 8097730
-------
Lab name: H&P
Client: tetra Tech
Analysis date: 10/14/2009 11:27:50
Method: SYRINGE
Lab ID: TT121608-T2
Description: CHANNEL 2 - ECD
Data file: C:\Peak329\1014ECD-26.CHR ()
Sample: ST3-MP-10'
Operator: T,S,
QC batch:
-204.800
2r
2048.000
- air/1.233
-/1.816
TCE/2.1QQ
- PCE/3.016
Component Retention Area External Internal
air
TCE
PCE
Units
1.233 11629.8640
2.100 5207.9640
3.016 3691.7460
358.8357
183.2187
13,0763
3588357
1007.7031 ug/m3
90.4883 ug/m3
20529.5740 555.1308 1457.0270
-------
Appendix D
Groundwater Sample Data
-------
Appendix D
Groundwater Sample Results Summary
(ug/L)
Sampling Round
November 2008
November 2008
November 2008
November 2008
November 2008
November 2008
November 2008
November 2008
November 2008
December 2008
December 2008
December 2008
December 2008
December 2008
December 2008
December 2008
December 2008
December 2008
January 2009
January 2009
January 2009
January 2009
January 2009
January 2009
January 2009
January 2009
January 2009
February 2009
February 2009
February 2009
February 2009
February 2009
February 2009
February 2009
February 2009
February 2009
March 2009
March 2009
March 2009
March 2009
March 2009
March 2009
March 2009
March 2009
March 2009
April 2009
April 2009
April 2009
April 2009
April 2009
April 2009
April 2009
April 2009
April 2009
May 2009
May 2009
May 2009
May 2009
May 2009
May 2009
May 2009
May 2009
June 2009
June 2009
June 2009
June 2009
June 2009
June 2009
June 2009
June 2009
June 2009
Sample ID
ST1-GW
ST2-GW
ST3-GW
ST4-GW
ST4-GWdup
ST5-GW
ST7-GW
ST8-GW
ST9-GW
ST1-GW
ST2-GW
ST3-GW
ST4-GW
ST5-GW
ST7-GW
ST7-GWdup
ST8-GW
ST9-GW
ST1-GW
ST2-GW
ST3-GW
ST4-GW
ST5-GW
ST7-GW
ST7-GWdup
ST8-GW
ST9-GW
ST1-GW
ST2-GW
ST3-GW
ST4-GW
ST5-GW
ST7-GW
ST7-GWdup
ST8-GW
ST9-GW
ST1-GW
ST2-GW
ST3-GW
ST4-GW
ST5-GW
ST7-GW
ST7-GWdup
ST8-GW
ST9-GW
ST1-GW
ST2-GW
ST3-GW
ST4-GW
ST5-GW
ST7-GW
ST7-GWdup
ST8-GW
ST9-GW
ST1-GW
ST2-GW
ST3-GW
ST4-GW
ST5-GW
ST7-GW
ST8-GW
ST9-GW
ST1-GW
ST2-GW
ST3-GW
ST4-GW
ST5-GW
ST7-GW
ST7-GWdup
ST8-GW
ST9-GW
TCE
310
82
40
0.81
ND
ND
500
190
12
420
85
45
0.84
ND
470
490
190
9.6
420
67
32
0.69
ND
460
450
150
8.7
310
74
34
0.6
ND
460
450
150
7.6
320
66
32
0.5
ND
380
340
110
5.9
360
66
28
0.5
ND
510
440
140
6.5
330
67
35
0.6
ND
510
160
7.7
390
75
32
0.6
ND
670
480
160
7.0
PCE
1.0
ND
ND
ND
ND
ND
2.8
ND
ND
1.4
ND
ND
ND
ND
2.6
2.7
ND
ND
1.2
ND
ND
ND
ND
1.9
2.1
ND
ND
0.9
0.4
ND
ND
ND
2.3
2.4
0.5
ND
1.1
0.4
ND
ND
ND
2.3
2.4
0.5
ND
1.4
0.6
0.2
ND
ND
3.1
2.5
0.8
ND
0.8
0.4
ND
ND
ND
2.7
0.6
ND
1.1
ND
ND
ND
ND
3.8
2.2
0.5
ND
1,1-DCA
2.2
ND
ND
ND
ND
ND
3.4
ND
ND
2.9
ND
ND
ND
ND
3.2
3.5
ND
ND
3.4
ND
ND
ND
ND
2.9
2.9
ND
ND
2.0
ND
ND
ND
ND
2.8
2.7
ND
ND
2.1
ND
ND
ND
ND
2.2
2.2
ND
ND
2.1
ND
ND
ND
ND
3.2
2.8
0.5
ND
ND
ND
ND
ND
ND
3.0
ND
ND
2.6
ND
ND
ND
ND
3.9
3.6
ND
ND
1,1-DCE
4.1
ND
ND
ND
ND
ND
3.7
1.8
ND
7.2
ND
ND
ND
ND
4.0
4.4
2.0
ND
7.8
ND
ND
ND
ND
3.2
3.3
1.1
ND
4.6
ND
ND
ND
ND
4.3
3.8
1.2
ND
4.6
ND
ND
ND
ND
3.2
3.4
ND
ND
4.4
0.8
ND
ND
ND
4.6
3.5
1.5
ND
2.5
ND
ND
ND
ND
3.0
1.3
ND
4.2
ND
ND
ND
ND
4.2
2.9
1.1
ND
c/s-l,2-DCE
5.4
ND
ND
ND
ND
ND
16
1.0
ND
7.0
ND
ND
ND
ND
15
18
ND
ND
7.2
ND
ND
ND
ND
13
13
ND
ND
4.3
ND
ND
ND
ND
13
13
ND
ND
4.5
ND
ND
ND
ND
11
11
ND
ND
4.7
ND
ND
ND
ND
15
14
0.8
ND
3.4
ND
ND
ND
ND
14
ND
ND
4.9
ND
ND
ND
ND
18
17
ND
ND
Benzene
ND
ND
ND
ND
ND
ND
ND
ND
ND
ND
ND
ND
ND
ND
ND
ND
ND
ND
ND
ND
ND
ND
ND
ND
ND
ND
ND
ND
ND
ND
ND
ND
ND
ND
ND
ND
ND
ND
ND
ND
ND
ND
ND
ND
ND
0.2
ND
ND
ND
ND
0.4
0.3
0.2
ND
ND
ND
ND
ND
ND
ND
ND
ND
ND
ND
ND
ND
ND
ND
ND
ND
ND
Toluene
ND
ND
ND
ND
ND
ND
ND
ND
ND
ND
ND
ND
ND
ND
ND
ND
ND
ND
ND
ND
ND
ND
ND
ND
ND
ND
ND
ND
ND
ND
ND
ND
ND
ND
ND
ND
ND
0.5
ND
ND
ND
ND
ND
ND
ND
0.3
0.4
0.5
ND
0.5
0.4
0.3
0.4
0.5
ND
ND
ND
ND
ND
ND
ND
ND
ND
ND
ND
ND
ND
ND
ND
ND
ND
Naphthalene
ND
ND
ND
ND
ND
ND
ND
ND
ND
ND
ND
ND
ND
ND
ND
ND
ND
ND
ND
ND
ND
ND
ND
ND
ND
ND
ND
ND
ND
ND
ND
ND
ND
ND
ND
ND
ND
ND
ND
ND
ND
ND
ND
ND
ND
ND
ND
ND
ND
ND
ND
ND
ND
ND
ND
ND
ND
ND
ND
ND
ND
ND
ND
ND
ND
ND
ND
ND
ND
ND
ND
Chloroform
3.3
1.5
ND
ND
ND
ND
4.8
2.0
ND
3.8
1.4
ND
ND
ND
4.4
4.9
1.9
ND
4.1
1.2
ND
ND
ND
4.3
4.2
1.7
ND
3.0
1.1
ND
ND
ND
4.0
4.1
1.7
ND
2.9
1.2
ND
ND
ND
3.5
3.5
1.6
ND
3.4
1.5
ND
ND
ND
4.8
4.4
1.9
ND
3.1
1.1
ND
ND
ND
4.5
1.8
ND
4.1
1.5
ND
ND
ND
6.1
5.2
2.0
ND
Chloromethane
ND
ND
ND
ND
ND
ND
ND
1.0
ND
ND
ND
ND
ND
ND
ND
ND
ND
ND
ND
ND
ND
ND
ND
ND
ND
ND
ND
ND
ND
ND
ND
ND
ND
ND
ND
ND
ND
ND
ND
ND
ND
ND
ND
ND
ND
ND
ND
ND
ND
ND
ND
ND
ND
ND
ND
ND
ND
ND
ND
ND
ND
ND
ND
ND
ND
ND
ND
ND
ND
ND
ND
All other VOCs
ND
ND
ND
ND
ND
ND
ND
ND
ND
ND
ND
ND
ND
ND
ND
ND
ND
ND
ND
ND
ND
ND
ND
ND
ND
ND
ND
ND
ND
ND
ND
ND
ND
ND
ND
ND
ND
ND
ND
ND
ND
ND
ND
ND
ND
ND
ND
ND
ND
ND
ND
ND
ND
ND
ND
ND
ND
ND
ND
ND
ND
ND
ND
ND
ND
ND
ND
ND
ND
ND
ND
App D, Page 1 of 2
<9/16/2010>
-------
Appendix D
Groundwater Sample Results Summary
(ug/L)
Sampling Round
July 2009
July 2009
July 2009
July 2009
July 2009
July 2009
July 2009
July 2009
July 2009
August 2009
August 2009
August 2009
August 2009
August 2009
August 2009
August 2009
September 2009
September 2009
September 2009
September 2009
September 2009
September 2009
September 2009
September 2009
September 2009
October 2009
October 2009
October 2009
October 2009
October 2009
October 2009
October 2009
October 2009
Sample ID
ST1-GW
ST2-GW
ST3-GW
ST4-GW
ST5-GW
ST7-GW
ST7-GWdup
ST8-GW
ST9-GW
ST1-GW
ST2-GW
ST3-GW
ST7-GW
ST7-GWdup
ST8-GW
ST9-GW
ST1-GW
ST2-GW
ST3-GW
ST4-GW
ST5-GW
ST7-GW
ST7-GWdup
ST8-GW
ST9-GW
ST1-GW
ST2-GW
ST3-GW
ST4-GW
ST5-GW
ST7-GW
ST8-GW
ST9-GW
TCE
430
93
37
0.4
ND
830
830
210
7.0
280
52
28
640
690
70
5.7
300
56
27
0.6
ND
490
360
130
7.6
360
35
22
0.5
ND
400
130
5.8
PCE
1.4
0.5
ND
ND
ND
4.2
4.4
0.8
ND
1.7
0.4
0.2
3.8
3.6
0.3
ND
1.4
0.4
ND
ND
ND
3.8
2.4
0.6
ND
1.4
ND
ND
ND
ND
3.6
0.8
ND
1,1-DCA
2.5
ND
ND
ND
ND
4.4
4.9
ND
ND
3.4
ND
ND
3.9
4.2
ND
ND
2.6
ND
ND
ND
ND
3.6
2.7
ND
ND
2.5
ND
ND
ND
ND
3.9
ND
ND
1,1-DCE
5.2
ND
ND
ND
ND
6.1
7.2
1.3
ND
8.0
ND
ND
4.5
5.0
ND
ND
6.7
ND
ND
ND
ND
4.8
2.8
1.8
ND
5.3
ND
ND
ND
ND
4.4
1.2
ND
c/s-l,2-DCE
5.0
ND
ND
ND
ND
23
26
ND
ND
6.8
ND
ND
20
22
ND
ND
6.0
ND
ND
ND
ND
21
17
ND
ND
5.8
ND
ND
ND
ND
23
1.1
ND
Benzene
ND
ND
ND
ND
ND
ND
ND
ND
ND
ND
ND
ND
ND
ND
ND
ND
ND
ND
ND
ND
ND
ND
ND
ND
ND
ND
ND
ND
ND
ND
ND
ND
ND
Toluene
ND
ND
ND
ND
ND
ND
ND
ND
ND
ND
ND
ND
ND
ND
ND
ND
ND
ND
ND
ND
ND
ND
ND
ND
ND
ND
ND
ND
ND
ND
ND
ND
ND
Naphthalene
ND
ND
ND
ND
ND
ND
ND
ND
ND
ND
ND
ND
ND
ND
ND
ND
ND
ND
ND
ND
ND
ND
ND
ND
ND
ND
ND
1.4
ND
ND
ND
ND
ND
Chloroform
3.7
1.6
ND
ND
ND
6.1
6.5
2.1
ND
4.4
1.5
ND
5.2
5.5
1.0
ND
3.7
1.3
ND
ND
ND
5.2
4.2
2.0
ND
3.6
1.4
ND
ND
ND
5.4
2.1
ND
Chloromethane
ND
ND
ND
ND
ND
ND
ND
ND
ND
ND
ND
ND
ND
ND
ND
ND
ND
ND
ND
ND
ND
ND
ND
ND
ND
ND
ND
ND
ND
ND
ND
ND
ND
All other VOCs
ND
ND
ND
ND
ND
ND
ND
ND
ND
ND
ND
ND
ND
ND
ND
ND
ND
ND
ND
ND
ND
ND
ND
ND
ND
ND
ND
ND
ND
ND
ND
ND
ND
Definitions:
|jg/L - micrograms per liter
DCA - dichloroethane
DCE - dichloroethene
ND - not detected
PCE - tetrachloroethene
TCE - trichloroethene
App D, Page 2 of 2
<9/16/2010>
-------
Appendix E
Soil Vapor Sample Data
-------
Appendix E
Soil Vapor Sample Results Summary
(ug/m3)
Sampling Round
November 2008
November 2008
November 2008
November 2008
November 2008
November 2008
November 2008
November 2008
November 2008
November 2008
November 2008
November 2008
November 2008
November 2008
November 2008
November 2008
November 2008
November 2008
November 2008
November 2008
November 2008
November 2008
November 2008
November 2008
November 2008
November 2008
November 2008
November 2008
November 2008
November 2008
November 2008
November 2008
November 2008
November 2008
November 2008
November 2008
December 2008
December 2008
December 2008
December 2008
December 2008
December 2008
December 2008
December 2008
December 2008
December 2008
December 2008
December 2008
December 2008
December 2008
December 2008
December 2008
December 2008
December 2008
December 2008
December 2008
December 2008
December 2008
December 2008
December 2008
December 2008
December 2008
December 2008
December 2008
December 2008
December 2008
December 2008
December 2008
Location
ST-1
ST-1
ST-1
ST-1
ST-1
ST-2
ST-2
ST-2
ST-2
ST-2
ST-3
ST-3
ST-3
ST-3
ST-4
ST-4
ST-4
ST-4
ST-5
ST-5
ST-5
ST-5
ST-7
ST-7
ST-7
ST-7
ST-7
ST-8
ST-8
ST-8
ST-8
ST-8
ST-9
ST-9
ST-9
ST-9
ST-1
ST-1
ST-1
ST-1
ST-1
ST-2
ST-2
ST-2
ST-2
ST-2
ST-3
ST-3
ST-3
ST-3
ST-4
ST-4
ST-4
ST-4
ST-5
ST-5
ST-5
ST-5
ST-7
ST-7
ST-7
ST-7
ST-7
ST-8
ST-8
ST-8
ST-8
ST-8
Depth
SS
2
4
7
10
SS
2
4
7
10
2
4
7
10
2
4
7
10
2
4
7
10
SS
2
4
7
10
SS
2
4
7
10
2
4
7
10
SS
2
4
7
10
SS
2
4
7
10
2
4
7
10
2
4
7
10
2
4
7
10
SS
2
4
7
10
SS
2
4
7
10
Macro TCE
PLUGGED
8,350
37,600
56,000
90,000
PLUGGED
200
1,000
2,700
2,500
PLUGGED
110
197
60
ND
ND
16
ND
ND
ND
ND
ND
4,400
40,000
60,000
92,000
165,000
230
4,450
8,300
14,700
30,000
24
46
44
315
460
9,800
52,000
80,000
103,000
72
71
1,600
4,250
4,200
62
140
315
93
ND
ND
ND
ND
ND
ND
ND
48
4,300
55,000
130,000
190,000
350,000
290
7,400
24,500
41,000
55,000
Micro TCE
NA
8,900
64,000
210
38
NA
280
1,900
3,100
1,400
36
ND
330
300
ND
ND
ND
ND
ND
ND
ND
ND
NA
66,000
158,000
87,000
53,000
NA
6,900
4,100
8,600
7,300
ND
ND
15
35
NA
6,700
38,000
NO SAMPLE
NO SAMPLE
NA
210
1,140
2,700
1,300
22
ND
270
270
ND
ND
ND
ND
ND
ND
ND
ND
NA
30,000
96,000
27,500
114,000
NA
2,400
8,200
9,500
9,400
Macro PCE
PLUGGED
180
780
1,400
2,500
PLUGGED
40
170
215
PLUGGED
70
90
165
ND
ND
39
60
ND
ND
ND
ND
ND
900
1,300
3,500
4,500
ND
150
260
370
800
12
30
40
110
13
185
1,000
1,900
2,300
ND
13
100
170
290
17
50
110
165
ND
ND
19
25
ND
ND
ND
47
70
1,100
2,700
5,600
11,000
18
175
520
1,000
1,250
Micro PCE
NA
310
1,700
ND
22
NA
90
200
300
180
19
ND
130
130
ND
ND
ND
ND
ND
ND
ND
ND
NA
2,400
5,100
3,400
2,700
NA
450
230
230
170
ND
74
30
30
NA
200
940
NO SAMPLE
NO SAMPLE
NA
32
100
145
130
18
ND
80
83
ND
16
16
18
ND
ND
ND
ND
NA
930
2,700
950
4,250
NA
80
110
300
320
App E, Page 1 of 7
<9/16/2010>
-------
Appendix E
Soil Vapor Sample Results Summary
(ug/m3)
Sampling Round
December 2008
December 2008
December 2008
December 2008
January 2009
January 2009
January 2009
January 2009
January 2009
January 2009
January 2009
January 2009
January 2009
January 2009
January 2009
January 2009
January 2009
January 2009
January 2009
January 2009
January 2009
January 2009
January 2009
January 2009
January 2009
January 2009
January 2009
January 2009
January 2009
January 2009
January 2009
January 2009
January 2009
January 2009
January 2009
January 2009
January 2009
January 2009
January 2009
January 2009
February 2009
February 2009
February 2009
February 2009
February 2009
February 2009
February 2009
February 2009
February 2009
February 2009
February 2009
February 2009
February 2009
February 2009
February 2009
February 2009
February 2009
February 2009
February 2009
February 2009
February 2009
February 2009
February 2009
February 2009
February 2009
February 2009
February 2009
Location
ST-9
ST-9
ST-9
ST-9
ST-1
ST-1
ST-1
ST-1
ST-1
ST-2
ST-2
ST-2
ST-2
ST-2
ST-3
ST-3
ST-3
ST-3
ST-4
ST-4
ST-4
ST-4
ST-5
ST-5
ST-5
ST-5
ST-7
ST-7
ST-7
ST-7
ST-7
ST-8
ST-8
ST-8
ST-8
ST-8
ST-9
ST-9
ST-9
ST-9
ST-1
ST-1
ST-1
ST-1
ST-1
ST-2
ST-2
ST-2
ST-2
ST-2
ST-3
ST-3
ST-3
ST-3
ST-4
ST-4
ST-4
ST-4
ST-5
ST-5
ST-5
ST-5
ST-7
ST-7
ST-7
ST-7
ST-7
Depth
2
4
7
10
ss
2
4
7
10
SS
2
4
7
10
2
4
7
10
2
4
7
10
2
4
7
10
SS
2
4
7
10
SS
2
4
7
10
2
4
7
10
SS
2
4
7
10
SS
2
4
7
10
2
4
7
10
2
4
7
10
2
4
7
10
SS
2
4
7
10
Macro TCE
23
34
41
370
660
9,100
30,000
64,000
84,000
33
95
1,200
2,600
2,700
44
93
230
83
ND
ND
ND
ND
ND
ND
ND
ND
4,100
57,000
97,000
130,000
200,000
290
6,700
23,000
30,000
52,000
ND
20
34
260
820
9,500
22,000
54,000
53,000
125
186
1,600
2,900
2,840
19
56
210
77
ND
ND
ND
ND
ND
ND
ND
ND
4,500
44,000
85,000
130,000
150,000
Micro TCE
12
44
28
35
NA
2,500
39,000
46,000
66,000
NA
170
1,470
1,220
960
20
ND
300
250
ND
ND
ND
ND
Probe removed
Probe removed
Probe removed
Probe removed
NA
32,000
110,000
57,000
78,000
NA
1,100
7,600
9,600
12,100
ND
25
27
67
NA
3,500
28,500
32,000
44,000
NA
86
1,240
1,500
105
ND
ND
135
98
ND
ND
ND
ND
Probe removed
Probe removed
Probe removed
Probe removed
NA
26,000
110,000
75,000
47,000
Macro PCE
24
43
65
110
ND
140
450
1,100
1,450
ND
ND
42
90
140
ND
ND
39
61
ND
ND
ND
ND
ND
ND
ND
ND
58
1,000
1,700
3,400
4,700
ND
130
340
490
820
ND
ND
19
44
ND
165
230
940
1,100
ND
18
57
87
210
ND
14
42
71
ND
ND
11
19
ND
ND
ND
ND
80
1,000
2,300
4,300
5,000
Micro PCE
36
100
60
34
NA
64
640
890
1,400
NA
ND
58
56
130
ND
ND
38
46
ND
ND
ND
ND
Probe removed
Probe removed
Probe removed
Probe removed
NA
610
2,900
1,340
2,400
NA
48
70
160
216
ND
ND
16
ND
NA
68
530
750
1,100
NA
10
34
60
10
ND
ND
20
20
ND
ND
ND
ND
Probe removed
Probe removed
Probe removed
Probe removed
NA
570
3,000
2,600
1,900
App E, Page 2 of 7
<9/16/2010>
-------
Appendix E
Soil Vapor Sample Results Summary
(ug/m3)
Sampling Round
February 2009
February 2009
February 2009
February 2009
February 2009
February 2009
February 2009
February 2009
February 2009
March 2009
March 2009
March 2009
March 2009
March 2009
March 2009
March 2009
March 2009
March 2009
March 2009
March 2009
March 2009
March 2009
March 2009
March 2009
March 2009
March 2009
March 2009
March 2009
March 2009
March 2009
March 2009
March 2009
March 2009
March 2009
March 2009
March 2009
March 2009
March 2009
March 2009
March 2009
March 2009
March 2009
March 2009
March 2009
March 2009
April 2009
April 2009
April 2009
April 2009
April 2009
April 2009
April 2009
April 2009
April 2009
April 2009
April 2009
April 2009
April 2009
April 2009
April 2009
April 2009
April 2009
April 2009
April 2009
April 2009
April 2009
April 2009
Location
ST-8
ST-8
ST-8
ST-8
ST-8
ST-9
ST-9
ST-9
ST-9
ST-1
ST-1
ST-1
ST-1
ST-1
ST-2
ST-2
ST-2
ST-2
ST-2
ST-3
ST-3
ST-3
ST-3
ST-4
ST-4
ST-4
ST-4
ST-5
ST-5
ST-5
ST-5
ST-7
ST-7
ST-7
ST-7
ST-7
ST-8
ST-8
ST-8
ST-8
ST-8
ST-9
ST-9
ST-9
ST-9
ST-1
ST-1
ST-1
ST-1
ST-1
ST-2
ST-2
ST-2
ST-2
ST-2
ST-3
ST-3
ST-3
ST-3
ST-4
ST-4
ST-4
ST-4
ST-5
ST-5
ST-5
ST-5
Depth
SS
2
4
7
10
2
4
7
10
SS
2
4
7
10
SS
2
4
7
10
2
4
7
10
2
4
7
10
2
4
7
10
SS
2
4
7
10
SS
2
4
7
10
2
4
7
10
SS
2
4
7
10
SS
2
4
7
10
2
4
7
10
2
4
7
10
2
4
7
10
Macro TCE
510
7,700
26,000
27,000
34,000
ND
ND
15
165
270
6,547
53,000
65,000
83,000
17
53
1,200
2,800
3,100
ND
32
110
38
ND
ND
ND
ND
ND
ND
ND
ND
6,100
69,000
130,000
136,000
126,000
557
12,000
28,000
33,000
34,000
ND
ND
ND
75
370
24000
53000
74000
76000
ND
NO SAMPLE
1900
3500
3200
32
84
290
87
ND
ND
ND
ND
ND
ND
ND
ND
Micro TCE
NA
2,300
7,100
7,900
11,000
ND
ND
ND
16
NA
2,000
81,000
94,000
130,000
NA
58
1,400
1,900
200
13
ND
100
110
10
ND
ND
12
Probe removed
Probe removed
Probe removed
Probe removed
NA
55,000
200,000
150,000
79,000
NA
3,000
9,300
21,000
20,000
14
ND
25
30
NA
NO SAMPLE
72000
83000
51000
NA
76
1800
2000
1000
ND
ND
140
80
ND
ND
ND
11
Probe removed
Probe removed
Probe removed
Probe removed
Macro PCE
ND
150
400
450
570
ND
15
23
47
ND
43
490
550
780
ND
ND
24
40
74
ND
10
22
33
ND
ND
ND
11
ND
ND
ND
ND
40
640
1,200
1,500
1,400
ND
110
200
280
160
ND
ND
11
20
ND
350
670
1000
1100
ND
NO SAMPLE
53
78
93
ND
15
32
46
ND
10
ND
11
ND
ND
ND
ND
Micro PCE
NA
41
73
110
190
ND
ND
10
ND
NA
26
600
710
1,300
NA
ND
20
26
21
ND
ND
12
22
ND
ND
ND
ND
Probe removed
Probe removed
Probe removed
Probe removed
NA
540
2,200
1,600
1,000
NA
28
54
110
160
ND
ND
7
ND
NA
NO SAMPLE
1100
1300
2600
NA
17
19
27
24
ND
ND
15
20
ND
ND
ND
ND
Probe removed
Probe removed
Probe removed
Probe removed
App E, Page 3 of 7
<9/16/2010>
-------
Appendix E
Soil Vapor Sample Results Summary
(ug/m3)
Sampling Round
April 2009
April 2009
April 2009
April 2009
April 2009
April 2009
April 2009
April 2009
April 2009
April 2009
April 2009
April 2009
April 2009
April 2009
May 2009
May 2009
May 2009
May 2009
May 2009
May 2009
May 2009
May 2009
May 2009
May 2009
May 2009
May 2009
May 2009
May 2009
May 2009
May 2009
May 2009
May 2009
May 2009
May 2009
May 2009
May 2009
May 2009
May 2009
May 2009
May 2009
May 2009
May 2009
May 2009
May 2009
May 2009
May 2009
May 2009
May 2009
May 2009
May 2009
June 2009
June 2009
June 2009
June 2009
June 2009
June 2009
June 2009
June 2009
June 2009
June 2009
June 2009
June 2009
June 2009
June 2009
June 2009
June 2009
June 2009
June 2009
Location
ST-7
ST-7
ST-7
ST-7
ST-7
ST-8
ST-8
ST-8
ST-8
ST-8
ST-9
ST-9
ST-9
ST-9
ST-1
ST-1
ST-1
ST-1
ST-1
ST-2
ST-2
ST-2
ST-2
ST-2
ST-3
ST-3
ST-3
ST-3
ST-4
ST-4
ST-4
ST-4
ST-5
ST-5
ST-5
ST-5
ST-7
ST-7
ST-7
ST-7
ST-7
ST-8
ST-8
ST-8
ST-8
ST-8
ST-9
ST-9
ST-9
ST-9
ST-1
ST-1
ST-1
ST-1
ST-1
ST-2
ST-2
ST-2
ST-2
ST-2
ST-3
ST-3
ST-3
ST-3
ST-4
ST-4
ST-4
ST-4
Depth
SS
2
4
7
10
SS
2
4
7
10
2
4
7
10
SS
2
4
7
10
SS
2
4
7
10
2
4
7
10
2
4
7
10
2
4
7
10
SS
2
4
7
10
SS
2
4
7
10
2
4
7
10
SS
2
4
7
10
SS
2
4
7
10
2
4
7
10
2
4
7
10
Macro TCE
8300
110000
212000
210000
210000
850
17000
39000
38000
41000
ND
13
10
110
500
NO SAMPLE
41000
63000
66000
62
NO SAMPLE
2500
4000
3400
48
200
700
280
ND
ND
ND
ND
ND
ND
ND
ND
4000
120000
230000
220000
220000
740
4700
32000
34000
31000
23
24
21
280
370
NO SAMPLE
NO SAMPLE
67,000
78,000
20
NO SAMPLE
1,800
3,100
2,400
130
300
520
350
ND
ND
ND
ND
Micro TCE
NA
65000
190000
160000
22000
NA
5000
16000
18000
12000
ND
ND
ND
14
NA
NO SAMPLE
52000
NO SAMPLE
47000
NA
860
2800
2800
1300
13
ND
300
99
ND
ND
ND
11
Probe removed
Probe removed
Probe removed
Probe removed
NA
66000
190000
160000
46000
NA
5000
7500
15000
7800
ND
ND
10
ND
NA
NO SAMPLE
30,000
27,000
25,000
NA
810
2,700
1,800
1,100
48
NO SAMPLE
480
290
ND
ND
ND
ND
Macro PCE
140
1700
3500
3900
3900
13
290
510
500
570
ND
13
16
27
23
NO SAMPLE
860
1700
1800
ND
NO SAMPLE
130
170
210
10
47
88
110
ND
15
19
24
ND
ND
ND
ND
130
4000
7400
8000
7700
24
160
830
850
820
34
25
42
71
ND
NO SAMPLE
NO SAMPLE
2,300
2,500
ND
NO SAMPLE
110
160
150
18
42
58
83
ND
14
18
18
Micro PCE
NA
1100
4000
3100
880
NA
49
120
220
170
ND
ND
ND
ND
NA
NO SAMPLE
1500
NO SAMPLE
1600
NA
56
110
97
81
12
ND
36
22
13
13
ND
13
Probe removed
Probe removed
Probe removed
Probe removed
NA
2200
6600
5600
2000
NA
140
110
390
250
ND
11
12
ND
NA
NO SAMPLE
1,000
900
700
NA
86
140
87
70
15
NO SAMPLE
45
39
ND
ND
ND
ND
App E, Page 4 of 7
<9/16/2010>
-------
Appendix E
Soil Vapor Sample Results Summary
(ug/m3)
Sampling Round
June 2009
June 2009
June 2009
June 2009
June 2009
June 2009
June 2009
June 2009
June 2009
June 2009
June 2009
June 2009
June 2009
June 2009
June 2009
June 2009
June 2009
June 2009
July 2009
July 2009
July 2009
July 2009
July 2009
July 2009
July 2009
July 2009
July 2009
July 2009
July 2009
July 2009
July 2009
July 2009
July 2009
July 2009
July 2009
July 2009
July 2009
July 2009
July 2009
July 2009
July 2009
July 2009
July 2009
July 2009
July 2009
July 2009
July 2009
July 2009
July 2009
July 2009
July 2009
July 2009
July 2009
July 2009
August 2009
August 2009
August 2009
August 2009
August 2009
August 2009
August 2009
August 2009
August 2009
August 2009
August 2009
August 2009
August 2009
August 2009
Location
ST-5
ST-5
ST-5
ST-5
ST-7
ST-7
ST-7
ST-7
ST-7
ST-8
ST-8
ST-8
ST-8
ST-8
ST-9
ST-9
ST-9
ST-9
ST-1
ST-1
ST-1
ST-1
ST-1
ST-2
ST-2
ST-2
ST-2
ST-2
ST-3
ST-3
ST-3
ST-3
ST-4
ST-4
ST-4
ST-4
ST-5
ST-5
ST-5
ST-5
ST-7
ST-7
ST-7
ST-7
ST-7
ST-8
ST-8
ST-8
ST-8
ST-8
ST-9
ST-9
ST-9
ST-9
ST-1
ST-1
ST-1
ST-1
ST-1
ST-2
ST-2
ST-2
ST-2
ST-2
ST-3
ST-3
ST-3
ST-3
Depth
2
4
7
10
ss
2
4
7
10
SS
2
4
7
10
2
4
7
10
SS
2
4
7
10
SS
2
4
7
10
2
4
7
10
2
4
7
10
2
4
7
10
SS
2
4
7
10
SS
2
4
7
10
2
4
7
10
SS
2
4
7
10
SS
2
4
7
10
2
4
7
10
Macro TCE
ND
ND
ND
ND
3,400
100,000
180,000
190,000
170000
460
16,000
34,000
33,000
35,000
23
35
24
260
400
NO SAMPLE
NO SAMPLE
NO SAMPLE
95,000
83
NO SAMPLE
NO SAMPLE
5,800
4,000
100
24
1,100
600
ND
ND
ND
ND
ND
NO SAMPLE
ND
ND
114
NO SAMPLE
230,000
270,000
300,000
690
18,000
48,000
50,000
46,000
ND
47
44
206
300
NO SAMPLE
NO SAMPLE
NO SAMPLE
NO SAMPLE
43
NO SAMPLE
NO SAMPLE
4,500
3,900
150
12
1,030
530
Micro TCE
Probe removed
Probe removed
Probe removed
Probe removed
NA
28,000
82,000
49,000
6,800
NA
4,800
8,500
7,300
2,800
ND
26
19
30
NA
NO SAMPLE
40,000
34,000
26,000
NA
2,000
5,300
3,700
2,600
59
ND
960
560
Probe removed
Probe removed
Probe removed
Probe removed
Probe removed
Probe removed
Probe removed
Probe removed
NA
31,000
103,000
66,000
20,000
NA
15,000
5,000
8,500
7,000
ND
29
25
75*
NA
NO SAMPLE
34,000
27,000
24,000
NA
1,500
4,000
4,100
1,400
72
NO SAMPLE
1,040
540
Macro PCE
ND
ND
ND
ND
97
4,900
8,400
8,900
6,600
16
690
1,200
1,100
1,100
21
31
33
44
17
NO SAMPLE
NO SAMPLE
NO SAMPLE
3,104
ND
NO SAMPLE
NO SAMPLE
460
230
28
ND
150
150
ND
ND
24
30
ND
NO SAMPLE
ND
ND
ND
NO SAMPLE
8,600
10,000
11,000
25
750
1,600
1,600
1,400
29
52
73
82
15
NO SAMPLE
NO SAMPLE
NO SAMPLE
NO SAMPLE
ND
NO SAMPLE
NO SAMPLE
250
250
33
ND
140
140
Micro PCE
Probe removed
Probe removed
Probe removed
Probe removed
NA
1,200
3,600
1,900
340
NA
140
140
190
83
21
27
25
19
NA
NO SAMPLE
1,500
1,200
920
NA
170
440
200
160
11
ND
106
120
Probe removed
Probe removed
Probe removed
Probe removed
Probe removed
Probe removed
Probe removed
Probe removed
NA
1,600
4,600
2,700
970
NA
600
130
300
280
ND
30
28
29*
NA
NO SAMPLE
1,400
1,000
880
NA
120
160
160
92
22
NO SAMPLE
104
90
App E, Page 5 of 7
<9/16/2010>
-------
Appendix E
Soil Vapor Sample Results Summary
(ug/m3)
Sampling Round
August 2009
August 2009
August 2009
August 2009
August 2009
August 2009
August 2009
August 2009
August 2009
August 2009
August 2009
August 2009
August 2009
August 2009
August 2009
August 2009
August 2009
August 2009
August 2009
August 2009
August 2009
August 2009
September 2009
September 2009
September 2009
September 2009
September 2009
September 2009
September 2009
September 2009
September 2009
September 2009
September 2009
September 2009
September 2009
September 2009
September 2009
September 2009
September 2009
September 2009
September 2009
September 2009
September 2009
September 2009
September 2009
September 2009
September 2009
September 2009
September 2009
September 2009
September 2009
September 2009
September 2009
September 2009
September 2009
September 2009
September 2009
September 2009
October 2009
October 2009
October 2009
October 2009
October 2009
October 2009
October 2009
October 2009
October 2009
October 2009
Location
ST-4
ST-4
ST-4
ST-4
ST-5
ST-5
ST-5
ST-5
ST-7
ST-7
ST-7
ST-7
ST-7
ST-8
ST-8
ST-8
ST-8
ST-8
ST-9
ST-9
ST-9
ST-9
ST-1
ST-1
ST-1
ST-1
ST-1
ST-2
ST-2
ST-2
ST-2
ST-2
ST-3
ST-3
ST-3
ST-3
ST-4
ST-4
ST-4
ST-4
ST-5
ST-5
ST-5
ST-5
ST-7
ST-7
ST-7
ST-7
ST-7
ST-8
ST-8
ST-8
ST-8
ST-8
ST-9
ST-9
ST-9
ST-9
ST-1
ST-1
ST-1
ST-1
ST-1
ST-2
ST-2
ST-2
ST-2
ST-2
Depth
2
4
7
10
2
4
7
10
ss
2
4
7
10
SS
2
4
7
10
2
4
7
10
SS
2
4
7
10
SS
2
4
7
10
2
4
7
10
2
4
7
10
2
4
7
10
SS
2
4
7
10
SS
2
4
7
10
2
4
7
10
SS
2
4
7
10
SS
2
4
7
10
Macro TCE
NO SAMPLE
NO SAMPLE
11
14
ND
NO SAMPLE
ND
ND
NO SAMPLE
NO SAMPLE
180,000
230,000
220,000
440
11,000
35,000
42,000
39,000
24
63
31
290
1,200
NO SAMPLE
NO SAMPLE
NO SAMPLE
NO SAMPLE
36
NO SAMPLE
NO SAMPLE
NO SAMPLE
21,000
430
NO SAMPLE
NO SAMPLE
2,000
ND
ND
15
24
ND
ND
ND
ND
NO SAMPLE
NO SAMPLE
NO SAMPLE
710,000
680,000
NO SAMPLE
36,000
110,000
110,000
110,000
33
120
150
790
2,100
NO SAMPLE
NO SAMPLE
NO SAMPLE
NO SAMPLE
1,100
NO SAMPLE
NO SAMPLE
NO SAMPLE
5,800
Micro TCE
Probe removed
Probe removed
Probe removed
Probe removed
Probe removed
Probe removed
Probe removed
Probe removed
NA
30,000
77,000
54,000
23,000
NA
11,000
4,000
7,400
4,500
ND
21
44
76
NA
NO SAMPLE
82,000
89,000
76,000
NA
6,100
13,000
8,300
4,300
750
NO SAMPLE
3,000
3,000
Probe removed
Probe removed
Probe removed
Probe removed
Probe removed
Probe removed
Probe removed
Probe removed
NA
100,000
240,000
180,000
120,000
NA
16,000
12,000
32,000
25,000
ND
29
24
150
NA
NO SAMPLE
40,000
42,000
41,000
NA
1,700
4,200
4,200
2,200
Macro PCE
NO SAMPLE
NO SAMPLE
35
41
ND
NO SAMPLE
ND
ND
NO SAMPLE
NO SAMPLE
8,000
11,000
10,000
20
500
1,400
1,500
1,300
31
61
70
73
21
NO SAMPLE
NO SAMPLE
NO SAMPLE
NO SAMPLE
ND
NO SAMPLE
NO SAMPLE
NO SAMPLE
820
40
NO SAMPLE
NO SAMPLE
240
ND
ND
42
54
ND
ND
ND
ND
NO SAMPLE
NO SAMPLE
NO SAMPLE
20,000
18,000
NO SAMPLE
870
2,500
2,600
2,300
34
91
110
130
37
NO SAMPLE
NO SAMPLE
NO SAMPLE
NO SAMPLE
24
NO SAMPLE
NO SAMPLE
NO SAMPLE
320
Micro PCE
Probe removed
Probe removed
Probe removed
Probe removed
Probe removed
Probe removed
Probe removed
Probe removed
NA
1,500
3,800
2,400
1,200
NA
560
130
300
180
19
34
50
36
NA
NO SAMPLE
1,700
1,900
1,500
NA
300
430
690
190
26
NO SAMPLE
170
300
Probe removed
Probe removed
Probe removed
Probe removed
Probe removed
Probe removed
Probe removed
Probe removed
NA
2,900
6,800
4,700
3,200
NA
400
200
720
540
15
35
19
44
NA
NO SAMPLE
940
1,000
940
NA
80
160
160
100
App E, Page 6 of 7
<9/16/2010>
-------
Appendix E
Soil Vapor Sample Results Summary
(ug/m3)
Sampling Round
October 2009
October 2009
October 2009
October 2009
October 2009
October 2009
October 2009
October 2009
October 2009
October 2009
October 2009
October 2009
October 2009
October 2009
October 2009
October 2009
October 2009
October 2009
October 2009
October 2009
October 2009
October 2009
October 2009
October 2009
October 2009
October 2009
Location
ST-3
ST-3
ST-3
ST-3
ST-4
ST-4
ST-4
ST-4
ST-5
ST-5
ST-5
ST-5
ST-7
ST-7
ST-7
ST-7
ST-7
ST-8
ST-8
ST-8
ST-8
ST-8
ST-9
ST-9
ST-9
ST-9
Depth
2
4
7
10
2
4
7
10
2
4
7
10
ss
2
4
7
10
SS
2
4
7
10
2
4
7
10
Macro TCE
120
NO SAMPLE
NO SAMPLE
1,100
NO SAMPLE
ND
NO SAMPLE
24
ND
NO SAMPLE
NO SAMPLE
ND
NO SAMPLE
NO SAMPLE
NO SAMPLE
300,000
330,000
NO SAMPLE
19,000
41,000
48,000
51,000
52
93
160
360
Micro TCE
150
NO SAMPLE
14,00
790
NO PROBE
NO PROBE
NO PROBE
NO PROBE
Probe removed
Probe removed
Probe removed
Probe removed
NA
40,000
95,000
82,000
50,000
NA
7,900
14,000
15,000
12,000
ND
NO SAMPLE
51
100
Macro PCE
12
NO SAMPLE
NO SAMPLE
170
NO SAMPLE
ND
NO SAMPLE
41
ND
NO SAMPLE
NO SAMPLE
ND
NO SAMPLE
NO SAMPLE
NO SAMPLE
11,000
12,000
NO SAMPLE
530
1,200
1,500
1,400
34
49
54
68
Micro PCE
21
NO SAMPLE
84
90
NO PROBE
NO PROBE
NO PROBE
NO PROBE
Probe removed
Probe removed
Probe removed
Probe removed
NA
1,100
2,600
2,200
1,600
NA
220
250
350
290
22
NO SAMPLE
39
32
Definitions:
,3
ug/m - micrograms per cubic meter
NA - not applicable (no sub-slab micro-purge probes)
ND - not detected
PCE - tetrachloroethene
SS - sub-slab
TCE - trichloroethene
App E, Page 7 of 7
<9/16/2010>
-------
Appendix F
Soil Vapor Profiles
-------
S -7 ST-1 ST 8 ST 2 ST-3 ST-9 ST-4 ST-5 LEGEND
u
1
2
4,400
40,000
3 1
. 1 60,000
5
6
i
UJ
E 7
92,000
8
9
10
1 1
1 O
i z
13
170,000
SLAB
230
8,400 |
| 4,500
^^^^
^38,000 P 8'300
^
56,000
90,000
|
15,000
,
30,000
200
1,000
2,700
i
2,500
J&/2/S
fff^^^^f^^^///
110
200
60
'ttftftfffift,
24
46
44
320
^UNPAVEDAREA^^^^
ND
ND
16
ND
%S^
ND
ND
ND
48
± |± ± ± t t ±
(180,000) * (11 0,000) |(67,000)| (29,000) | |(14,000) |(4,200) 5(280) ^ |
50 ± 31( ± 190± 82 ± ± 40 ± ±0.8 - ± ND
± I ± ± ± I I ±
i i i i i i i i
VERTICAL EXAGGERATION = 5X
6,500 TCE CONCENTRATIONS
IN SOIL VAPOR
FROM MACRO-PURGE
PROBES (pg/m3)
460 TCE CONCENTRATIONS
IN GROUNDWATER (fJg/L)
(240) HENRY'S LAW
EQUILIBRIUM TCE
CONCENTRATION IN SOIL
VAPOR (jjg/m3)
3
6
9
1 9
0
i
^^ :
^
^ k
i
E EE E
1
E \
E \
E --
\
E 3
E '^f \
E
10 20 30 40 50 60 70 80 90
FEET Nov. 2008
-------
0
ST-7 ST-1 ST-8 ST-2 ST-3 ST-9 ST-4 ST-5
4,300
2 55,000
3
4
5
6
h-
Ld
LJ -7
L_ /
8
9
10
11
12
13
130,000
190,000|
350,000|
SLAB
460
9,800
52,000
| 80, 000 |
| 100, 000 1
290
7,400
25,000
|41,000|
|55,000|
72
71
1,600
| 4,300|
| 4,200|
/ S J
/y/wy/v/v//
62
140
- '
,.. ,
^^yyyyyyy/^
23
34
,. ,
,. ,
^ UN PAVED Wty'/^/y/YSs
ND
ND
,..
,..
/ / / / .
w,
ND
ND
| ND
1 48
1
0. J- 4- 4- 4.
I I I I I
(160,000) If (1 50,000) 1(67,000)}: (30,000) I l(1 6,000) |(3,400) |(290) ^ I
| | | 85 | | 45 1 9.6 1 0.84 ~ | ND
t T t t t T T t
VERTICAL EXAGGERATION = 5X
LEGEND
6,500 TCE CONCENTRATIONS IN
SOIL VAPOR FROM MACRO-
PURGE PROBES (jjg/m3)
460 TCE CONCENTRATIONS IN
GROUNDWATER (fJg/L)
(240) HENRY'S LAW EQUILIBRIUM
TCE CONCENTRATION IN SOIL
VAPOR ((Jg/m3)
3
6
9
1 9
I Z.
0
,
10 20 30 40 50 60 70 80 90
FEET Dec. 2008
-------
0
2
A
*+
\
Ld
Ld
^ 6
8
10
ST-7 ST-1 ST-8 ST-2 ST-3 ST-9 ST-4 ST-5
4,100
57,000
97,000
130,000|
SLAB
660
9,100
^^
^L
30,000
| 64,000 1
290
6,700
^
^
23,000
| 30,000 1
33
95
1,200
| 2,600|
v s / / /
'/y/y/y//^/
44
93
,- ,
/y/y/y/y/y/
ND
20
,- ,
^//^///UNPAVED AREA^//
ND
ND
,ND ,
y/y/y/y/y/y/
ND
ND
I ND
84,000 1 52,000 1 2,70ol 1 83 1260 1 ND 1 ND
m
+ + ++ + + +
(160,000)+ (150,000)+ (53,000)+ (24,000)+ +(11,000) +(3,100) +(240) W +
I | 15 ± 67 1 ^32 |8.7 |0.69 = ^ND
1 illlii 1
VERTICAL EXAGGERATION = 5X
LEGEND
6,500 TCE CONCENTRATIONS
IN SOIL VAPOR
FROM MACRO-PURGE
PROBES ([Jg/m3)
460 TCE CONCENTRATIONS
IN GROUNDWATER (fJg/L)
(240) HENRY'S LAW
EQUILIBRIUM TCE
CONCENTRATION IN SOIL
VAPOR (|Jg/m3)
0| j 1
3
6
1
12
i
=1 E
" 67E
^32
E8.7
: '^f =
E0.69 *
END
0 10 20 30 40 50 60 70 80 90
FEET Jan. 2009
-------
n ST
U
1
4,500
9 44,000
z.
4 85,000
5
6
i
Ld
Ld -7
Li_ /
8
9
10
11
1 9
i z.
13
0
3
6
9
1 9
I .£.
c
130,000|
150,000.
7 ST
SLAB
820
9,500
^^
^^
22,000
| 54,000 |
- 53,000 -
1 ST
510
7,700
26,000
|27,000|
.34,000.
8 ST
125
186
1,600
| 2,900|
- 2,800.
2 ST
v//,
. .
-3 ST
^//^/^//
19
56
,- ,
,» -
-9 ST
/^//^/^//
ND
ND
. ,
,, ,
j-4 ST-5 i rnrkin
^UNPAVEp^AREA/^/^/^
ND
ND
,-
,-
'///,
ND
ND
| ND
- ND
4- 1 1 1 J- J- 1
I I I T I I
(160,000)1 (11 0,000) T (53,000)1 (26,000)1 1(12,000) £(2,700) l(210) ^ T
| | 15 \ 74 | | 34 \ 7.6 | 0.6 ' | ND
i ±±±±±± i
_l_ _k ^ ^ ^ ^ j_ J_
VERTICAL EXAGGERATION = 5X
1 1
'
^
£ I I I I X £ ^ X
= = = = = = = = =
6,500 TCE CONCENTRATIONS IN
SOIL VAPOR FROM MACRO-
PURGE PROBES (jjg/m3)
460 TCE CONCENTRATIONS IN
GROUNDWATER (fJg/L)
(240) HENRY'S LAW EQUILIBRIUM
TCE CONCENTRATION IN SOIL
VAPOR (pg/m3)
10 20 30 40 50 60 70 80 90 - onno
PEET Feb. 2009
-------
0
ST-7 ST-1 ST-8 ST-2 ST-3 ST-9 ST-4 ST-5
6,100
1
2 69,000
3 I
4
130,000
:
Ld
Ld 7
8
9
10
11
12
13
140, 000 1
SLAB
270
6,500
55,000
L 65,000 |
560
12,000
28,000
|33,000|
17
53
k 1 ,200
| 2,800|
y/y/
y/////////'
10
32
... ,
v/vyyyy/vy.
ND
ND
,- ,
^UNPAVED kKLty//////,
ND
ND
,-
////
ND
ND
| ND
83, 000 1 34,000 1 3,10ol 1 38 1 75 1 ND 1 ND
1 11111 1
t ± ± ± t ± ±
(130,000)1 (11 0,000) 1(39,000)1 (23,000) T 1(1 1,000)
:(2,100) jj(180) ^ T
I £ ^- £
380$ 320j 110 J 66 J } 32 | 5.9 j 0.5 q: ND
i ±±±±±± ±
VERTICAL EXAGGERATION = 5X
LEGEND
6,500 TCE CONCENTRATIONS IN
SOIL VAPOR FROM MACRO-
PURGE PROBES (Hg/m3)
460 TCE CONCENTRATIONS IN
GROUNDWATER (|Jg/L)
(240) HENRY'S LAW EQUILIBRIUM
TCE CONCENTRATION IN SOIL
VAPOR ([Jg/m3)
w
3
6
9
1 9
I Z
0
^^^^^^^m
=r
= a
= =
p =
c ^f
^
10 20 30 40 50 60 70 80 90
FEET March 2009
-------
0
'
2
'
4
5
6
i
Ld
E,
:
;;
1 2
13
0
3
6
9
12
0
ST
8,300
110,000
210,000
210,000|
210,000|
7 ST
SLAB
370
^24,000
53,000
| 74,000 1
| 76,000 1
1 ST
850
17,000
39,000
| 38,000 1
|41,000|
8 ST
ND
1,900
| 3,500|
| 3,200|
2 ST
v///
-3 ST
////y///^
52
84
1 29° 1
,- ,
-9 ST
/^//Y/////
ND
13
1 ,
,» ,
-4 ST
/^UNPAVED Wlk////////
ND
ND
,.
,.
-5
////
ND
ND
|ND
|ND
J. |1 1 1 J. J. 1
t t I I I t
(180,000) I (130,000)1(49,000)1 (23,000)1 1(9,800) I (2,300) I (180) W I
51i i 36cf $ 66 i j 28 | 6-5 T 3-5 ~ T ND
i i i i i i i i
VERTICAL EXAGGERATION = 5X
^_
I ;
i 1
.
,
I
i :
E i
i i
.
,
T
I
LEGEND
6,500 TCE CONCENTRATIONS IN
SOIL VAPOR FROM MACRO-
PURGE PROBES Gig/m3)
460 TCE CONCENTRATIONS IN
GROUNDWATER ((Jg/L)
(240) HENRY'S LAW EQUILIBRIUM
TCE CONCENTRATION IN SOIL
VAPOR (fjg/m3)
10 20 30 40 50 60 70 80 90
FEET April zuuy
-------
n ST-7 ST-1 ST-8 ST-2 ST-3 ST-9 ST-4 ST-5 | r^Tkin
4,000
^^
2
3
4
5
6
|y
8
9
10
11
1 7
13
120,000
230,000
220,000|
SLAB
500
k
41,000
| 63,000 |
740
4,700
32,000
| 34,000 1
62
2,500
| 4,000|
w,
W////M
48
200
,700 ,
W/////////.
23
24
,., ,
^UNPAVED^'REA;^^^/
ND
ND
,ND
W.
ND
ND
| ND
66, 000 1 31, 000 1 3,40ol 1280 1280 1 ND 1 ND
11111 1
I ± t t I I t
(180,000) I (120,000)1 (56,000) I (24,000) I 1(12,000) l(2,700) l(210) V I
51C J 33C f ^ 67 ^ ^ 35 f 7.7 f 0.6 ' J ND
I I I I I I I I
VERTICAL EXAGGERATION = 5X
6,500 TCE CONCENTRATIONS IN
SOIL VAPOR FROM MACRO-
PURGE PROBES Gig/m3)
460 TCE CONCENTRATIONS IN
GROUNDWATER (fJg/L)
(240) HENRY'S LAW EQUILIBRIUM
TCE CONCENTRATION IN SOIL
VAPOR (}Jg/m3)
3
6
9
1 9
I Z
0
n
10 20 30 40 50 60 70 80 90 ^OV 2009
-------
;
ST-7 ST-1 ST-8 ST-2 ST-3 ST-9 ST-4 ST-5
SLAB
3.400B 3701
\ 460
2 100,00ol 1 16,000
3
4
5
6
i
Ld
Ld-,
L_ /
8
9
10
11
12
13
0
3
6
9
12
(
180,OOoP P34,000
190, 000 J
| 67,000 |
|33,000|
20
1,800
| 3,100|
m
W//////S
130
300
,-
y//////////,
23
35
,, ,
/////////////////////
^UNPAVED k^k///////,
ND
ND
,-
m
ND
ND
| ND
78, 000^35,00ol 2,40ol ^350 ^260 ^ ND 1 ND
4- -I- 4- 4- 1 ± 4-
(240,000) T (1 40,000) J (56,000) T (26,000) £ T(1 1,000) ±(2,500) ±(210) ^ T
I ± -i ± = ±
670 ± 390 ± 1 60 ± ± ± 32 ± 7.0 ± ± ND
± ±±±±±t ±
j- i^ ^ ^ ^ ^ A. J-
VERTICAL EXAGGERATION = 5X
£ \
i
i
i E
i E
i i
V =
i
LEGEND
6,500 TCE CONCENTRATIONS IN
SOIL VAPOR FROM MACRO-
PURGE PROBES (jjg/m3)
460 TCE CONCENTRATIONS IN
GROUNDWATER (fJg/L)
(240) HENRY'S LAW EQUILIBRIUM
TCE CONCENTRATION IN SOIL
VAPOR (pg/m3)
) 10 20 30 40 ^^ 50 60 70 80 90 JunQ 2QQg
-------
0
1
2
3
4
5
6
jj
^ 7
8
9
10
11
12
13
0
3
6
9
12
(
ST-7 ST-1 ST-8 ST-2 ST.- 3 ST-9 ST-4 STr5
SLAB
11 4 400
^^^^^_
230,OOoP
270,OOoJ
690
18,000
^
48,000
|50,000|
83
| 5,800|
m
W///M
100
24
| 1,100 |
w/////////,
ND
47
,- ,
'//////////////////////.
^UN^AVED f AREA^/^/;
ND
ND
,H.
m
ND
ND
| ND
95, 000 1 46, 000 1 4,00ol 1 600 ^206 ^ ND 1 ND
111 1
I ± ± ± I I ±
(290,000) ± (150,000)1(74,000)1 (33,000) ± ±(13,000) 1(2,500) 1(140) ^ ±
83 T 430 T 21 if 93 T 5 37 q: 7.0 q: D.4 - T ND
T TTTTTT T
I ZIIIZZ I
VERTICAL EXAGGERATION = 5X
£ ;
E
E
E ;
E ;
E 3
'
T =
E
LEGEND
6,500 TCE CONCENTRATIONS IN
SOIL VAPOR FROM MACRO-
PURGE PROBES (jjg/m3)
460 TCE CONCENTRATIONS IN
GROUNDWATER (fJg/L)
(240) HENRY'S LAW EQUILIBRIUM
TCE CONCENTRATION IN SOIL
VAPOR (Hg/m3)
D 10 20 30 40 50 60 70 80 90 ~nnn
FEET July 2009
-------
0
ST-7 ST-1 ST-8 ST-2 ST-3 ST-9 ST-4 ST-5
SLAB
300
2 if
3
4
5
6
^ 7
8
9
10
11
12
13
Oi
3
6
9
12
C
180,OOoP
230,000|
'
440
11,000
35,000
|42,000|
43
,
| 4,500|
M
W///////S
150
12
| 1 ,000 |
w/////////,
24
63
,. ,
^UNl'WD'AREA^^:
|
/%,
ND
| ND
Isg.OOol 3,90ol 1 530 ^290 ^14 1 ND
ll 1 1 J. J. 1
(220,000) I (98,000) T (25,000)1 (1 8,000)1 T (9,800) T (2,000) T ^ T
64 \ i \ 52 \ \ 28 i 5.7 i )RY ~ \ ND
± ±±±±±± ±
J- J- J- J- J- J- J- _l_
VERTICAL EXAGGERATION = 5X
=
P =
i
i
,
= 3
P =
P =
P 3
P 9
^ ;
= = = = = = = = =
LEGEND
6,500 TCE CONCENTRATIONS IN
SOIL VAPOR FROM MACRO-
PURGE PROBES (jjg/m3)
460 TCE CONCENTRATIONS IN
GROUNDWATER (fJg/L)
(240) HENRY'S LAW EQUILIBRIUM
TCE CONCENTRATION IN SOIL
VAPOR (Mg/m3)
) 10 20 30 40 50 60 70 80 90 onnn
FEET August 2009
-------
Appendix G
Statistical Analyses
-------
Appendix G
EPA STREAMS TO-85
Statistical Analyses of Micro-Purge versus Macro-Purge Data
Percent of Macro-purge measurements measured at each station that exceed the
Micro-purge measurements by more than a factor of two are listed below.
Location
ST-1
ST-2
ST-3
ST-7
ST-8
ST-9
Ratio
6/24
13/35
12/30
23/42
41/48
17/27
Percentage
25
37
40
55
85
63
The expectation is that the micro-purge versus macro-purge data will exhibit a 1:1
correlation, and they should be best described by a linear regression. However, it was
found that the power-law equations provided the best fit to the measurement data:
Y = axXb, where Y = Micro-purge measurement of TCE (ug/m3) and X = Macro-purge
measurement of TCE (ug/m3). Note that on a Log-Log plot, the power-law equation
reduces to a linear expression, where LnY = a + bLnX. The values of the fitted
coefficients and the resultant R-square values are listed on each figure shown.
Data grouped by depth using the power-law model Y = axXb
The upper and lower lines represent the 95% confidence interval about the fitted power-
law curve.
probe_2ft
Y = a*xb
r2=0.7939693S DF Adj r2=0.782S232 FitSMErr*S998.0175 Fstat*142.S8493
3=3.5770316 ; b=O.S361662
70000
60000
I
'gSOOOO
'40000
a:
g, 30000
a
O_
e 20000
o
'm
10000
25000 50000 75000 1e+05
Macro-Purge Results (jig/m3)
1,25e*05
G-1
-------
probe_4ft
Y = a*xt>
r2=0.65273926 DF Adj r^=0 63537622 FitStdErr=34580.004 Fstat=77.066903
a=9.7365767 ; b=0 78398594
2e+05
1.756+05
i 1.5e+05
M.256+05
i
i
1e+05
I
i 75000
i
i 50000
25000
50000 1e+05 1.56+05 2e+05
Macro-Purge Results (ng/m3)
2.56+05
probe_7ft
Y = 3*X»
r'=0.69176444 DF Adj r2=0.68075603 FitStdErr=25227.987 Fstat=127.9235
a=27.S68869; b=0.65411895
2e+05 4e+05 66+05
Macro-Purge Results (ng/m3)
Se+os
probe_10ft
Y = a*x»
r2=0.57527089 DFAdjr2=0.56199811 FitStdErr=19867 341 Fstat=88.038722
8=24.733439 ; b=0.62470502
1.56+05
1.256+05
1e+05
rr 75000
50000
25000
26+05 4e+05
Macro-Purge Results (tig/m3)
6e*05
G-2
-------
probe_AII depths
Y = a*xb
r2=0.5S313936 DF Adj r2=O.S4S77974 FSStdErr=27S04.571 Fstat=254.993S3
8=54.179364; b=O.S9S21345
2e*OS ie-OS 6e-0£
Macro-Purge Results (ug/m3)
Data grouped by month using the power-law model 7 = ax xb
Note that September, October, and November are fitted with a linear regression model
7 = a + bX since the power-law model failed to converge. The upper and lower lines
represent the 95% confidence interval about the fitted power-law curve.
Month_January
Y = a'Xb
r2=0. 76578736 DF Adjr2=0.7411334 FitStdErr=1 5649.364 Fstat=65.3924S9
8=16.074126; b=0.71084532
1.25e+05
ce
1e+05
^ 75000
B 50000
25000
50000 1e+05 1.5e+05
Macro-Purge Results (ug/m3)
2e+05
G-3
-------
Month_February
Y = a*X»
r2=0.6704E214 DF Adj 1-2=0.62925866 FitStdErr=17787.857 Fstat=34.585831
8=10.843301 ; b*0.74493061
1.256+05
1e+05
S 75000
50000
25000
50000 1e+05
Macro-Purge Results (ng/m3)
LEe-OE
Month_March
Y = a*xb
r2=0.84013808 DF Adjr2=0.82015534 FitStdErr=25129.284 Fstat=89.341772
3=0.5143308; 6=1.0684236
2e+05
1.756+05
£ 1.56+05
a 1.256+05
Q
tr 16+05
-------
Month_May
Y = a*Xb
f2=0.76917042 DF Adj r2=0.73619476 FitStd£rr=28297.936 Fstat=49.983005
3=056240473
b=1.0046869
2e+05
50000
1e--05 1.5e"-05
Macro-Purge Results (tig/m3)
2e*05
2.5e+05
Month_June
Y = a'Xb
r2=0.6609238S DF Adj r^=0.61853937 FitStdErr=12826.739 Fstat=33.136235
3=0.37967528; b=0.97047783
90000
10000
50000 1e+05 1.5e*05
Macro-Purge Results (ug/m3)
2e»05
Month_July
Y = a*Xb
r2=0.60381782 DF Adj r2=0.54286671 FltStdErr=18624.336 Fstat=21.337278
8=64664247; b=0 72772742
1.25e*05
1e*05
75000
Q_
6
50000
25000
le-OE 2e»OE
Macro-Purge Results (|jg/m3)
3e+05
G-5
-------
Month_August
Y = a'X"
r2=0.7078704 DF Adjr2=0.6S91B213 FitStdErr=12759.601 Fstat=31.500797
a=1.6S3106S; b=0 8376588
SOOOO
70000
: 60000
£. 50000
cc 40000
=)30000
Q_
.a 20000
s
10000
0
50000 1e+05 1.5e+OS
Macro-Purge Results (ng/m3)
Ee*05
r2=0. 95254425
Month_September
Y = a + b*X
DFAdj r2=0.941 99853 FitStdErr=1 3068. 743 Fstat=200.72264
8=843.3641 ; b=0.21518382
2e-05
1.75e-f05
1 1.5e+05
I
^ 1.256+05
B
Q.
1e+05
75000
50000
25000
0
2e+05 4e+05 6e+05
Macro-Purge Results (iig/m^)
8e+05
Month_October
Y = a + b*x
r2=0.88664217 DF Adj r2=0.85-830271 FltStdErr=9236.0306 Fstat=70.394601
a=2168.5025 ; b=0.20129243
90000
80000
^70000
g
-60000
H
±r
I 50000
K
^40000
5 30000
o
S 20000
10000
0
1e+05 2e+05
Macro-Purge Results (Mg/m3)
3e+05
G-6
-------
Month_November
Y = a + b*X
r2=0.25295529 DF Adjr2=0.16506768 FitStdErr=36990.538 Fstat=6.094943S
3=6811.1346; b=0.48121553
s
ce
1.756+05
1.56+05
i 125e+05
1e+OS
75000
5
Qu
e soooo
25000
0
50000 1e»05
Macro-Purge Results (ng/m3)
1.56+05
Month_December
Y = a*X"
r2=0.78090295 DF Adj r2*0.756S58S4 FitStdErr=1S133.698 Fstat=67.719562
a=49154258; b=0 7833338
1.256+05
ff 16+05
75000
P 50000
CL
O
25000
1e+05 2e+05
Macro-Purge Results (ug/m3)
36+05
Data grouped by location using the power-law model Y = axXb
Note that location ST-7 was not fitted since the power-law model failed to converge.
The upper and lower lines represent the 95% confidence interval about the fitted power-
law curve.
G-7
-------
Station_ST1
Y = a*X>=
r2=0.248S6838 DF Adj r2=0.18355259 FitStdErr=29275.762 Fstat=7.9517904
3=125.76912; b=O.S3975234
1.5e*05
1 25e*OS
3 1e«05
s
11
3
O.
&
75000
50000
25000
20000 40000 60000 80000 le-HJS
Macro-Purge Results (ug/m3)
Station_ST2
Y = a«Xb
r2=0.50831015 DF Adj r2=0.47757953 FitStdErr=S05.S930S Fstat=34.115479
a=42.704545; b=0.46924583
4500
4000
5000 10000 15000
Macro-Purge Results
20000
25000
Station_ST3
Y = a*Xb
r2=0.90544485 DF Adj r2=0.89844076 FitStdErr=177.69414 Fstat=268.12347
3=0.038481908; b=1.4735831
3000
500 1000 1500
Macro-Purge Results (^ig/rn3)
2000
G-8
-------
Station ST7
2e+05
_ 1.756+05
H 1.5e+05
|j 1.25e+05-
£ 1e+05-
I" 75000-
CL
g 50000-
1
25000-
2e+05 4e+05 6e+05
Macro-Purge Results (ng/m3)
8e+05
Station_ST8
r2=0.40752942 DFAdj f2=0.381 19739 FSStdErr=4761.0663 Fstat=31. 640986
8=16.750243; b-0.61 433242
35000
30000
g25000
20000
tr
S 15000
^
£L
810000
o
S
5000
25000 50000 75000 1e+05
Macro-Purge Results (|jg/m3)
1,25e*05
Station_ST9
Y = a*X»
r2=0.61449406 DF Adj r2=0.5S236S56 FltStdErr=19.694454 Fstat=39.549844
3=1.4391547; b=0.66913301
|"
100
&
3
w
S. 75
I
-------
-------
&EPA
United States
Environmental Protection
Agency
Office of Research
and Development (8101R)
Washington, DC 20460
Official Business
Penalty for Private Use
$300
EPA/600/R-10/118
October 2010
www.epa.gov
Please make all necessary changes on the below label,
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------- |