EPA/600/R-17/459 I September 2018 ! www.epa.gov/research
Comparative Evaluation of Contaminant Mass Flux
and Groundwater Flux Measurements in Fractured
Rock Using Passive Flux Meters
United States
Environmental Protection
Agency
PROJECT REPORT
Office of Research and Development
National Risk Management Research Laboratory
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AUTHORS
CDM Smith
John N. Dougherty
Tamzen Macbeth
Brendan MacDonald
RTI International
Robert Truesdale
University of Florida
Mark A. Newman
Jaehyun Cho
Michael Annable
US Environmental
Protection Agency
Diana Cutt
Katherine Mishkin
Michael C. Brooks
Site photographs taken on location at the
former Naval Air Warfare Center (NAWC),
West Trenton, New Jersey
June 2015
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CONTENTS
DISCLAIMER iv
ACKNOWLEDGMENTS iv
ACRONYMS iv
ABSTRACT v
SECTION 1 Introduction 1-1
1.1 Purpose 1-1
1.2 Roies and responsibilities 1-2
1.3 Methods for estimating groundwater flux and mass flux 1-3
1.4 Definition of groundwater flux and mass flux 1-4
1.5 Test well selection and site hydrogeology 1-7
1.5.1 Test well selection 1-7
1.5.2 Site hydrogeology 1-9
SECTION 2 Methods 2-1
2.1 Overview 2-2
2.2 Borehole Dilution Test 2-5
2.3 Modified Standard Passive Flux Meter 2-7
2.3.1 Description 2-7
2.3.2 Insertion/Retrieval test 2-7
2.3.3 Deployment, retrieval, and sampling 2-9
2.4 Fractured Rock Passive Flux Meter 2-11
2.4.1 Description 2-11
2.4.2 Deployment, retrieval, and sampling 2-13
SECTION 3 Results and Synthesis 3-1
3.1 Existing borehole geophysical data review 3-1
3.2 Borehole Dilution Test 3-2
3.3 Insertion/Retrieval test 3-5
3.4 Modified Standard Passive Flux Meter 3-5
3.4.1 Quantification limit 3-5
3.4.2 Sample results 3-5
3.5 Fractured Rock Passive Flux Meter 3-7
3.5.1 Quantification limit 3-7
3.5.2 Sample results 3-7
3.5.3 Results of analysis of fabric sleeve for fracture flow information 3-9
3.6 Comparisons between methods 3-10
3.7 Comparisons to common borehole geophysical methods 3-14
SECTION 4 Conclusions and Recommendations 4-1
4.1 Borehole Dilution Test 4-2
4.2 Modified Standard Passive Flux Meter 4-3
4.3 Fractured Rock Passive Flux Meter 4-3
SECTION 5 References 5-1
APPENDIX Data Quality Assurance and Quality Control A-l
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FIGURES
Figure 1-1 Conceptual illustration of the basis for groundwater and contaminant flux measurement using BHD, MSPFMs, and FRPFMs 1-6
Figure 1-2 Location maps 1-7
Figure 1-3 Site location relative to Lockatong Formation 1-9
Figure 1-4 Conceptual depiction of geologic stratigraphy near well 68BR 1-10
Figure 2-1 Schematic depiction of test methods: a) BHD test, b) MSPFM, c) FRPFM 2-2
Figure 2-2 Tripod used to install and remove equipment from well 68BR and blank FLUTe™ liner 2-4
Figure 2-3 BHD test rig and deployment in well 68BR 2-5
Figure 2-4 MSPFM insertion/retrieval test 2-8
Figure 2-5 MSPFM assembly and deployment 2-9
Figure 2-6 MSPFM retrieval sampling 2-10
Figure 2-7 FRPFM components 2-12
Figure 2-8 FRPFM assembly and deployment 2-14
Figure 2-9 FRPFM retrieval and sampling 2-16
Figure 2-10 Image of FRPFM under the black light 2-17
Figure 3-1 Rock core from location 68BR collected by the USGS 3-1
Figure 3-2 Well 68BR borehole geophysical data and rock matrix VOC results 3-3
Figure 3-3 BHD test results 3-4
Figure 3-4 MSPFM results 3-6
Figure 3-5 FRPFM results 3-8
Figure 3-6 FRPFM groundwater flux comparison 3-9
Figure 3-7 Comparison of BHD test, MSPFM and FRPFM results 3-12
Figure 3-8 Comparison of borehole geophysical and sample data and BHD test, MSPFM, and FRPFM results 3-14
Figure 3-9 Flexible petal used to channel flow through a heat pulse flow meter 3-15
TABLES
Table 2-1 Summary of activities 2-3
Table 2-2 BHD test sequence of events 2-6
Table 3-1 Low flow and BHD test sample results 3-2
Table 3-2 Comparison of the BHD test, MSPFM, and FRPFM Results 3-11
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DISCLAIMER
This document has been reviewed in accordance with U.S. Environmental Protection Agency policy
and approved for publication. Any mention of trade names or commercial products does not constitute
endorsement or recommendation for use.
ACKNOWLEDGMENTS
We gratefully acknowledge the assistance provided by Daniel Goode, Tom Imbrigiotta, Pierre Lacombe,
and Savannah Miller with the U.S. Geological Survey for complete access to hydrogeologic information
on the fractured bedrock research site as well as technical and other assistance given during the project.
Completion of this project would not have been possible without their assistance and support. Likewise,
we acknowledge and thank Eric Daiber, formerly an EPA Student Services Contractor; and Russell Neill,
William Sy, and Steve Vandegrift with the EPA for their support and assistance with this project. Internal
technical review comments from Randall Ross and Kathy Davies with the EPA, as well as external peer
review comments from Daniel Goode with the USGS and Todd Halihan from Oklahoma State University
are greatly appreciated and were used to improve the report. Finally, we thank Kathy Tynsky with AttainX
for document production support.
ACRONYMS
ATV
Acoustic Televiewer
bgs
Below Ground Surface
BHD
Borehole Dilution
cm
centimeters
DCE
cis-l,2-dichloroethene
DNAPL
Dense Non-Aqueous
Phase Liquid
EPA
United States
Environmental
Protection Agency
ft
feet
FLUTe™
Flexible Underground
Liner Technology
FRPFM
Fractured Rock Passive
Flux Meter
gpm
Gallon per Minute
HPFM
Heat Pulse Flow Meter
in
inch
KCI
Potassium Chloride
KVA
K-V Associates, Inc.,
presently known as
Kerfoot Technologies, Inc.
LPM
Liters per Minute
m
meters
M-g/L
micrograms per liter
mg/L
milligrams per liter
mm
millimeters
mS/cm
milliSiemens per centimeter
MSPFM
Modified Standard Passive
Flux Meter
NAWC
Naval Air Warfare Center
ORD
Office of Research and
Development
OTV
Optical Televiewer
PFM
Passive Flux Meter
PVC
Polyvinyl Chloride
QAPP
Quality Assurance
Project Plan
QA/QC
Quality Assurance/
Quality Control
RARE
Regional Applied
Research Effort
RPD
Relative Percent
Difference
TCE
Trichloroethene
TOC
Top of Casing
UF
University of Florida
USGS
U.S. Geological Survey
VOC
Volatile Organic
Compound
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ABSTRACT
Cost effective and reliable techniques are needed for the characterization of contaminated fractured
rock aquifers. Two important characteristics of contaminant transport are groundwater velocity (or flux)
and contaminant mass flux. Conventional methods for characterization in fractured rock cannot directly
measure groundwater or contaminant mass flux. Therefore, the purpose of this project was to assess
the ability of two technologies, the modified standard passive flux meter (MSPFM) and the fractured
rock passive flux meter (FRPFM), to measure groundwater and contaminant mass flux in fractured rock.
These measurements were compared to more conventional fractured rock characterization methods,
including a borehole dilution (BHD) test. The comparative study of these techniques was conducted
in a well at the former Naval Air Warfare Center Research site located in West Trenton, New Jersey.
This research site, which consists of fractured sedimentary rock, is operated by the U.S. Geological
Survey (USGS) as part of the USGS Toxic Substances Hydrology Program. Tests conducted in the well
centered on a transmissive fracture identified at 28.7 m (94 ft) below ground surface through previous
characterization activities.
Average groundwater flux measurements from the BHD test, MSPFM, and FRPFM were 1.5 cm/day,
2.6 cm/day, and 2.7 cm/day, respectively. Estimates of groundwater flux based on the MSPFM and
FRPFM were very similar, but were almost a factor of two higher than the BHD test results.
Measurements of groundwater flux vertical distributions were also completed with the MSPFM and
FRPFM. However, the spatial patterns of groundwater flux as measured with the MSPFM and FRPFM
were not similar. Average trichloroethene mass flux measurements from the BHD test, MSPFM, and
FRPFM were 18.8 mg/m2/day, 31.5 mg/m2/day, and 116 mg/m2/day, respectively. Likewise, average
cis-l,2-dichloroethene mass flux measurements from the BHD test, MSPFM, and FRPFM were
14.6 mg/m2/day, 40.7 mg/m2/day, and 68.2 mg/m2/day, respectively. In both cases, the BHD gave the
lowest estimates while the FRPFM gave the highest. As with groundwater flux, spatial measurements
of contaminant flux based on the MSPFM and FRPFM were not similar. Differences in results between
the technologies most likely stem from differences in measurement design and method, but natural
variability in conditions during the tests may also be a factor. Moreover, damage to the FRPFM during
retrieval may also have been a factor in the results obtained.
The MSPFM, compared to the FRPFM, was easier to implement, and is judged less likely to be damaged
during deployment and retrieval. However, because of its design it is also more susceptible to sampling
bias during deployment and retrieval. The FRPFM was the most complex method to use compared to the
MSPFM and BHD test. The FRPFM was damaged during retrieval in this study, suggesting this technology
is more fragile than the BHD test or MSPFM. At present, the best use for the FRPFM would be those
applications where high resolution data is needed over short intervals. Further development of the
FRPFM technology may result in a more widely applicable measurement method. Comparisons of the
spatial distributions of groundwater flux and contaminant mass flux between the MSPFM and FRPFM as
measured in this project indicate more research is needed to further assess the accuracy and reliability
of the measured spatial distributions. Controlled experiments in which the true distribution is known
would be helpful in this regard.
V
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SECTION 1
Introduction
1.1 Purpose
At contaminated groundwater sites, groundwater
flux or specific discharge (q ) and contaminant
mass flux (J ) are important parameters that
can be used to understand the significance of
contaminant loading to an aquifer, evaluate
contaminant fate and transport, assess risk,
design a groundwater remediation system, and
assess remedial performance. The purpose
of this project, funded by the United States
Environmental Protection Agency (EPA) Office
of Research and Development's (ORD) Regional
Applied Research Effort (RARE), was to:
• Assess the ability of the modified standard
passive flux meter (MSPFM) and the
fractured rock passive flux meter (FRPFM)
to measure qg andJ in a fractured bedrock
setting, and
• Compare and contrast the MSPFM and
FRPFM results with results obtained using
investigative methods typically deployed
at sites to characterize fractured bedrock
hydrogeology. These methods include
open-hole methods: borehole geophysical
logging, vertical component borehole
flow meter under pumped and ambient
conditions, Flexible Underground Liner
Technology (FLUTe™) transmissivity profile,
dilution testing, and low flow or wireline
groundwater sampling at various depths;
and a closed-hole method: packer testing/
sampling.
Work on this project was conducted in
accordance with the Quality Assurance Project
Plan (QAPP) prepared by EPA (EPA, 2015). This
report details the results of this project and
provides a comparative evaluation of the MSPFM
and FRPFM technologies relative to conventional
fractured rock characterization methods,
including an assessment of how easily the
technologies can be adopted at other fractured
rock sites.
1-1
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1.2 Roles and responsibilities
The project was performed by personnel from the University of Florida (UF) and CDM Smith with technical
oversight from the EPA ORD and the EPA Region 2 Superfund Program, The MSPFM is an adaptation of
the passive flux meter (PFM), which was patented by UF (Hatfield et al., 2002) and currently licensed
by EnviroFlux, LLC for commercial use. The FRPFM was patented by UF (Klammler et al., 2008) and is
not currently licensed for commercial use. Tasks to be completed by UF were specified in a sole-source
contract and tasks to be completed by CDM Smith were specified in Task Order Number 015 under
STREAMS II subcontract No. 9-312-0213151-51241L.
1-2
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1.3 Methods for estimating groundwater flux and mass flux
The borehole geophysical methods typically
deployed at sites to characterize fractured
bedrock hydrogeology, some of which are
described in Section 3.1, cannot directly
measure qg or/.
A borehole dilution (BHD) test, when
combined with groundwater sampling from
the test interval, can be used to estimate
qg and /. As explained in Section 2 of this
report a BHD test, using packers to isolate the
test interval, was used to calculate qg and to
collect samples for volatile organic compound
(VOC) analysis from the test interval. The use
of packers has the advantage of reducing or
eliminating vertical flow in the test interval
which otherwise interferes with accurate qg
measurements. The packers also allow VOC
concentrations to be determined in specific
zones.
Borehole dilution tests can also be conducted
in an open borehole using methods that rely
on either replacing the water in the borehole
with low conductivity, deionized water
(hydrophysical logging, Wilson et al., 2001),
by injecting salt solution (Michalski and
Klepp, 1990), or by introducing dye (Pitrak
et al., 2007). All of the open-hole methods
monitor the dilution process by running a
probe up and down the borehole repeatedly
to collect data on fluid conductivity or color
intensity. Collecting groundwater VOC data
from the open hole could be done with a
pump or, preferably, by packer sampling
after the dilution test is completed. Packer
sampling can isolate zones for sampling
from vertical flow in the borehole. Borehole
dilution methods are not commonly used in
many investigations at this time.
According to Hatfield (2015), while qg and/ can be
estimated from observed contaminant concentrations
in fractured rock boreholes and depth-averaged
groundwater flows calculated or measured under
open-hole conditions, this approach is not likely to
produce accurate estimates of qg and/ for at least two
reasons. First, the open borehole induces flow which
is not natural or ambient and second, the open-hole
methods take a "snap shot" at one point in time and
do not account for variations in flow and concentration
over time.
Open hole methods for estimating horizontal qg using
borehole flow meters and hydrophysical logging are
described in Wilson et al. (2001). The meters tested
included the KVA heat pulse flow meter, the colloidal
borescope, and the acoustic Doppler velocimeter in
addition to hydrophysical logging (which measures
fluid conductivity). These methods are not commonly
used for the specific purpose of estimating horizontal
qg in boreholes drilled in fractured bedrock at
Superfund sites because the vertical flow commonly
observed in these boreholes makes it difficult or
impossible to obtain useful estimates.
High resolution temperature logging can be conducted
in lined boreholes to locate and rank active (flowing)
fractures under closed-hole conditions (Pehme et al.,
2014). Closed-hole conditions can be approximated
using a FLUTe™ liner or packers to isolate borehole
sections (Cherry et al., 2007). The FLUTe™ liner seals
against the entire borehole wall thereby eliminating
the exchange of water and contaminant between
fractures that occurs in open boreholes and in turn
restores natural flows in fractures. At present, high
resolution temperature logging is not typically used
to characterize fractured bedrock boreholes at EPA
Superfund sites.
1-3
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1.4 Definition of groundwater flux and mass flux
Groundwater flux, also called specific discharge, Darcy flux, Darcy velocity or filtration velocity, is the
volumetric rate of flow per unit cross-sectional area. It is typically calculated using Darcy's law:
q0 = j = Ki (i-D
where
qg = groundwater flux [L/T],
K = horizontal hydraulic conductivity, [L/T]
/ = hydraulic gradient [L/L],
Q = volumetric groundwater discharge [L3/T], and
A = cross-sectional area [L2].
1-4
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Mass flux is the mass of a chemical (e.g., contaminants, amendments, and tracers) that passes through
a defined cross-sectional area over a period of time. Contaminant mass flux represents the amount
of contaminant mass transported by the volumetric groundwater discharge through a defined cross-
sectional area. Mass flux is expressed as mass per area per time [M/L2/T] (Kolditz, 2002; ITRC, 2010).
The mass fiux can be calculated as follows:
Jc = Ro * (l-2)
where
J = advective contaminant mass flux [M/L2/T], and
Cp = concentration of contaminant in the groundwater [M/L3].
Measures of qg and / are calculated directly from the MSPFM and FRPFM through tracer mass loss and
contaminant mass accumulation over the deployment duration. These measures represent time-average
values over the deployment duration. A detailed description of how q and / are calculated using flux
meter data may be found for the MSPFM in Hatfield et al. (2004), and for the FRPFM in Hatfield (2015).
However, Figure 1-1 provides a conceptual illustration of the measurement theory for each of these
methods as well as the BHD test. The ratio]Jqg can be used to calculate the flux-averaged contaminant
concentration, which is an estimate of the average contaminant aqueous concentration within the test
interval. The average represents both a temporal average over the deployment duration, and a spatial
average over the sampling interval. Estimates of q. and Cf were also obtained from a BHD test, and these
results are compared to the qg and Cf values calculated from the flux meters. Previous work has shown
good correlation between BHD and FRPFM results (Hatfield, 2015).
during BHD testing
Monitoring flowrates
MitUvtmmnm,
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WFlo i
Groundwater flux is
estimated from tracer
dilution, as determined
by measuring tracer
concentration time series.
Instantaneous mixing is
assumed, and typically
obtained using a pump.
Contaminant concentration
can also be measured in
the solution to estimate
contaminant flux.
Groundwater flux is
estimated from the change
in tracer mass over the
deployment period, while
contaminant flux is estimated
from the accumulation of
contaminant mass over
the deployment period.
These masses are based on
sampling the sorbent matrix
(shown here as granular
activated carbon) after the
deployment period.
Groundwater flux is
estimated from the change
in tracer mass over the
deployment period, while
contaminant flux is estimated
from the accumulation of
contaminant mass over
the deployment period.
These masses are based on
sampling the sorbent matrix
(shown here as permeable
carbon felt) after the
deployment period.
Initial Condition
After Deployment
Open space filled with
contaminant-free tracer solution.
Permeable granular carbon,
contaminant-free, loaded with tracer.
Diluted tracer solution with
contaminant due to
groundwater flow.
Blue shading represents tracer-free
region with sorbed contaminant due
to advective groundwater flow.
Blue shading represents tracer-free
region with sorbed contaminant due
to advective groundwater flow.
IV Hoi
Permeable carbon felt wrapped
around impermeable packer.
Figure 1-1. Conceptual illustration of the basis for groundwater and contaminant flux measurement
using BHD, MSPFMs, and FRPFMs. Shown are cross-sectional views of each device at the start of the
deployment and after a given deployment period. Groundwater flow is directed left to right.
Figure based on information provided in Hatfield et al., 2004, and Acar et al., 2013.
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Former Naval Air Warfa
CD <£'
1.5 Test well selection and site hydrogeology
1.5.1 Test well selection
The former Naval Air Warfare Center (NAWC) is a
24 hectare (60 acre) facility located in West Trenton,
New Jersey (Figure l-2a). The NAWC served as a naval
testing facility for aircraft jet engines from 1953 to 1994.
During its operation, trichloroethene (TCE) was used
as a heat exchange medium in testing aircraft engines
under various environmental conditions. The handling
and disposal of TCE at the site resulted in extensive
groundwater contamination (Lacombe, 2000).
The U.S. Geological Survey (USGS) operates the NAWC
Research Site as part of the USGS Toxic Substances
Hydrology Program and scientists and engineers from
the USGS and other institutions conduct research on
the characterization and remediation of chlorinated
solvents in fractured sedimentary rock (Lacombe and
Burton, 2010). At the NAWC site these rocks include
undifferentiated mudstones, massive mudstones,
laminated mudstones, and fissile mudstones.
Figure 1-2. Location maps.
(a) Former Naval Air Warfare
Center (NAWC).
(b) Pumping well 15BR,
test well 68BR,
and cross section F F'
location.
0 20 40 60 80 Meters
Selected Well Locations ^
- - - Cross section F - F*
Fence
Building
68BR&
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1-8
Weil 68BR at the NAWC Research Site (Figure l-2b) was selected by the project team as the test
borehole for this project because:
• It is a 0.2 m (6 inch [in]) borehole cased with 6-inch diameter steel to 4.0 m (13 feet [ft]) below
ground surface (bgs) with a 0.2 m (6 in) nominal diameter borehole extending to 52 m (170 ft) bgs.
This borehole size is optimum for the use of the current FRPFM system. The steel casing extends
0.43 m (1.4 ft) above land surface.
• Historically, groundwater samples from this well show high levels of TCE and cis-l,2-dichloroethene
(cis-l,2-DCE). In May 2009 TCE was detected in packer sampling interval "D" in well 68BR at
a concentration of 20,800 micrograms per liter ((ig/L) while cis-l,2-DCE was detected at a
concentration of 7,470 |ag/L (Geosyntec, 2010). interval D extends from 27.7 to 30.5 m (90.8 to
100.1 ft) bgs and includes the interval tested during this study.
• Various open-hole and closed-hole investigative methods typically deployed at EPA Superfund sites
to characterize fractured bedrock hydrogeology have been used in the borehole and the data sets
are available for comparison. These include: borehole geophysical data, a FLUTe™ transmissivity
profile, rock matrix sample results for TCE and other VOCs, and packer testing.
When weil 68BR is not in use, a blank
FLUTe™ liner is maintained in the borehole
by the USGS to prevent vertical movement
of groundwater and contaminants in the
borehole.
Presently, the U.S. Navy, under oversight
by the State of New Jersey, operates a
groundwater pump and treat system at
the NAWC site. Under typical pumping
conditions, well 68BR is hydraulically
influenced by the nearby pumping well
15BR (Figure l-2b), located approximately
100 m (300 ft) SW of 68BR. Before,
during, and after the BHD, the MSPFM
deployment, and the FRPRM deployment
conducted under this project, extraction
well 15BR was not operating. During the
time when 15BR was out of service, the
total system pumping rate was maintained
at the permitted level by increasing the
pumping rate of other extraction wells.
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1.5.2 Site hydrogeology
The NAWC site is underlain by sedimentary rocks in the Newark Basin (Figure 1-3). Soil and weathered rock
cover the site to a depth of approximately 4.6 m (15 ft). The water table varies from 1.5 to 4.6 m (5 to 15 ft)
bgs over the site (Lacombe, 2002). Well 68BR is completed in the Lockatong Formation which is bounded to
the south by a fault separating the Lockatong from the Stockton Formation. A conceptual depiction of the
site geology is shown in Figure 1-4.
Muds of the Lockatong Formation were deposited in Van Houten cycles during the Triassic Period,
approximately 200 million years ago, lithified to form the bedrock that is typical of much of the Newark
Basin. The four lithotypes include a basal red massive mudstone, black carbon-rich laminated mudstone,
dark-gray laminated mudstone, and an upper light-gray massive mudstone. Diagenesis, tectonic compression,
off-loading, and weathering have altered the rocks to give some strata greater hydraulic conductivity than
other strata (Lacombe and Burton, 2010).
mm-
LotfiKatong
Formation (
0 5 10 15 20 25 30 33 40 45 KILOMETERS
0 5 10 15 20 25 MILES
Figure 1-3. Site location relative to Lockatong Formation.
Map courtesy of U.S. Department of the Interior j USGS
1-9
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Each stratum in the Lockatong Formation is 0.3 to 8 m (1 to 26 ft) thick, strikes N65°E, and dips 25°
to 70°NW. The black, carbon- rich laminated mudstone is the more extensively fractured strata, has a
relatively high hydraulic conductivity, and is associated with high natural gamma-ray count rates. The
dark-gray laminated mudstone is less fractured and has a lower hydraulic conductivity than the black
carbon-rich iaminated mudstone. The iight-gray and the red massive mudstones are highly indurated
and tend to have the least fractures and a low hydraulic conductivity (Lacombe and Burton, 2010).
The detailed hydrogeologic framework developed for the site shows that black carbon-rich laminated
mudstones are the most hydraulically conductive. Water-quality and aquifer-test data indicate that
groundwater flow is greatest and TCE contamination is highest in the black, carbon- and clay-rich
laminated mudstones. Large-scale groundwater flow at the NAWC research site can be modeled as
highly anisotropic with the highest component of hydraulic conductivity occurring along bedding planes
(Lacombe and Burton, 2010; Tiedeman et al., 2010).
\
F
NW
MASSIVE AND
LAMINATED
MUDSTONES
UNDIFFERENTIATED
LOCKATONG
MUDSTONES
NOT TO SCALE
1-10
Figure 1-4. Conceptual depiction of geologic stratigraphy near well 68BR.
Adapted from Tiedeman et al., 2010, and Lacombe and Burton, 2010.
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SECTION 2
Methods
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2.1 Overview
The BHD test, along with deployment, retrieval and sampling of the MSPFM and FRPFM, were
conducted in accordance with the QAPP prepared by EPA (EPA, 2015) and procedures developed by UF
(Hatfield, 2015). Each of these methods is illustrated in Figure 2-1. The BHD test, MSPFM, and FRPFM
deployments were centered on a target depth of 29.0 m (95.1 ft) bgs. This depth was selected to be
consistent with previous work conducted using the FRPFM in this borehole (Hatfield, 2015) and is 0.3 m
(1 ft) below the transmissive fracture identified at 28.7 m (94 ft) bgs in previous geophysical iogging of
the borehole (see Section 3.1). The fracture is in a fissile black shale approximately 0.3 m (1 ft) thick
which extends from 28.7 to 29.0 m (94 to 95 ft) bgs. Analysis of the acoustic televiewer (ATV) log by CDM
Smith shows that the dip azimuth is 1.7 degrees, and the dip angle is 32 degrees.
BHD Test
Connecting Borehole
Wall
Open
Borehole
Not to scale
Rods
Pump
Tubing
Figure 2-1. Schematic depiction of test methods: a) BHD, b) MSPFM, and c) FRPFM.
2-2
FRPFM
MSPFM
Central
Support Rod
Activated
Carbon
Borehole
Wall
Annular
Space
PVC Well Screen
c)
Inflatable
Packer
Wall
Plastic Mesh
Borehole
Wall
Fabric
Sleeve
Carbon
Felt
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Table 2-1 lists the start and finish date of each element of field work
conducted during this project.
Table 2-1 Summary of activities
Date
Activities and comments
6/1/15
Install borehole dilution rig in 68BR. Pump
does not work. Retrieve rig, check and fix
pump, probably clogged with sediment.
6/2/15
Install borehole dilution rig and start BHD.
Test interval 28.4 to 29.5 m
(93.3 to 96.9 ft) bgs.
6/3/15
Monitor BHD and collect groundwater samples
for VOC analysis.
6/4/15
Complete BHD, remove BHD rig from well,
conduct insertion/retrieval test using MSPFM.
6/5/15
Deploy MSPFM from 27.4 to 30.7 m
(89.9 to 100.6 ft) bgs.
6/5/15 -
6/23/15
MSPFM deployed.
6/23/15
MSPFM retrieved and sampled.
6/24/15
FRPFM assembled and deployed. Test interval
28.6 to 29.5 m (93.7 to 96.7 ft) bgs.
6/24/15
-7/1/15
FRPFM deployed.
7/1/15
FRPFM retrieved and sampled.
2-3
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A specialized tripod provided by UF was used to install and remove equipment from the well.
Prior to starting the test the blank FLLITe™ liner installed in 68BR was removed (Figure 2-2).
Tripod
Winch
Well 68BR
—r
Blank FLUTe™ Liner
\ —
Figure 2-2. Tripod used to install and remove equipment from well 68BR and blank FLUTe™ liner.
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2.2 Borehole Dilution Test
A BHD test was conducted to estimate the specific discharge and concentration of cis-l,2-DCE and ICE in the test
interval. These target compounds were chosen because TCE was used extensively at the site and because cis-l,2-DCE
is a degradation product of TCE. To conduct the BHD test, UF deployed a custom built rig in the borehole (Figure 2-3).
The rig includes packers at the top and bottom which isolate a 1.1 m (3.6 ft) long test interval.
After correcting a problem with the pump on 6/1/2015, the rig was deployed on 6/2/2015. The rig was installed so
that the test interval extended from 28.4 to 29.5 m (93.3 to 96.9 ft) bgs with the center of the test interval at 29.0 m
(95.1 ft) bgs. The packers were then inflated to isolate the test zone and the submersible pump was used to pump
water from the test interval at a low flow rate of 0.5 to 1 liters per minute (LPM). The flow rate was regulated using the
variable speed motor on the pump and a flow meter. The water was pumped from the well, through two conductivity
meters in series and then discharged to a drum for disposal in the on-site treatment plant. Over the course of the
next two hours a series of groundwater samples were collected for VOC analysis to assess the pre-dilution test VOC
concentrations in the test zone. At the end of this period, the ambient electrical conductivity of 0.491 milliSiemens per
centimeter (mS/cm) was measured. Then valves were used to recirculate water pumped to the surface, and through
the conductivity meters, back down the tubing and into the test zone. One liter of potassium chloride (KCI) tracer
solution, prepared using groundwater pumped from the well, was injected into the recirculating water, a peak specific
conductance of 9.44 mS/cm was observed and the BHD was started at 12:44 EDT on 6/2/2015.
Inlet for Recirculation
Bottom Packer
Grundfos Redi-Flo 2
Submersible Pump ||
t N,
Air Line to Inflate
Packers
Deployment
in well 68BR
Top Packer
Support
Hardware
-------
During the test, groundwater samples were collected at regular intervals for VOC analysis and the conductivity of the
water was monitored, and the data logged continuously, using two meters to provide redundancy. After 42.5 hours
from the start of the BHD, the conductivity had dropped to 6.72 mS/cm, and the test was stopped as sufficient data
had been collected to define a log-linear trend in the conductivity-time series data. Table 2-2 lists the BHD sequence
of events. The data were then analyzed using the procedure described in Pitrak et al. (2007) to calculate qg. The
results of the BHD are discussed in Section 3.1. The calculated qg was used to estimate an appropriate deployment
time for the MSPFM and FRPFM.
Table 2-2 BHD test sequence of events
Date
Time
(EDT)
Elapsed Time
(hours)
Activity
Sample
Numbers
(See note)
6/2/15
08:55
Static Water Level: 2.46 m (8.08 ft) below top of casing (TOC)
6/2/15
08:57
Begin Installation BHD rig, target depth 29.4 m (96.5 ft) below TOC
6/2/15
09:48
-
Packers Inflated
6/2/15
10:05
-
Start purging test zone, flow rate 0.5 LPM
6/2/15
10:10
0
Low Flow Sampling, flow rate 0.73 LPM
1, 2, 3
6/2/15
10:46
0.6
Low Flow Sampling
4, 5, 6
6/2/15
11:36
1.43
Low Flow Sampling
7, 8, 9
6/2/15
11:43
1.55
Prepare 1 L of saturated KCI solution using water purged from well
6/2/15
12:12
2.03
Low Flow Sampling, 80 L pumped from test zone
10, 11, 12
6/2/15
12:14
2.07
Stop pumping from and start recirculating water in the test zone
6/2/15
12:19
2.15
Baseline conductivity established at 0.491 mS/cm
6/2/15
12:39
2.48
Add concentrated KCI solution to test interval start BHD
6/2/15
12:44
2.57
Start BHD, conductivity 9.44 mS/cm
6/2/15
19:00
8.83
BHD Sampling
1, 2, 3
6/3/15
07:00
20.83
BHD Sampling
4, 5, 6
6/3/15
13:00
26.83
BHD Sampling
7, 8, 9
6/3/15
14:44
28.57
Depth to water: 2.26 m (7.40 ft) below TOC (see note)
6/3/15
19:00
32.83
BHD Sampling
10, 11, 12
6/4/15
07:00
44.83
BHD Sampling
13
6/4/15
07:15
45.08
BHD stopped, total duration 2,550 minutes (42.5 hours)
Samples were analyzed for VOCs. The observed decrease in depth to water between 6/2/15, before the test, and 6/3/15,
during the test, was probably due to the inflation of the packers which isolated the fracture at 28.7 m (94 ft) bgs. This
fracture has a lower head than the fractures in the shallow zone (see Section 3.1). Blocking the lower head fracture
increased the head in the borehole and therefore decreased the depth to water.
2-6
-------
2.3 Modified Standard Passive Flux Meter
2.3.1 Description
The MSPFM consists of a standard PFM placed inside a 0.1 m (4 in) diameter factory slotted
poly-vinyl chloride (PVC) pipe to protect it from the abrasive borehole wall. A standard PFM,
designed for unconsolidated sediments, consists of a central PVC pipe, norprene divider rings,
and sorbent material packed inside a mesh sock. In the case of organic contaminants, the
sorbent material is typically activated carbon, as it was in this study. The sorbent material
retains dissolved contaminants present in the groundwater flowing passively through the
meter. The contaminant mass intercepted and retained on the sorbent is used to quantify
cumulative contaminant mass flux. The sorbent material is also impregnated with known
amounts of water soluble alcohol tracers. These tracers are displaced from the sorbent at
rates proportional to the specific discharge; hence, the amount of tracer remaining after
deployment can be compared to the original amount and the results used to estimate the
groundwater flux (Hatfield et al., 2004).
An important difference between applications of the MSPFM in fractured rock formations
compared to either applications of the standard PFM in unconsolidated sediments or the
FRPFM in fractured rock formations, is that the sorbent of the MSPFM does not actually
come in contact with the borehole wall. The design of the MSPFM which protects it from the
abrasive borehole wall results is an annular space between the device and the borehole wall
(see Figure 2-1). This annular space allows water to preferentially flow around the device, and
this may impact measurements. Another noteworthy difference between the MSPFM and the
FRPFM is the deployment time. Deployment times were estimated prior to deployment based
on site specific estimates of groundwater flux, and were 18 days for the MSPFM and
7 days for the FRPFM.
2.3.2 Insertion/Retrieval test
An "insertion/retrieval" test was conducted to determine how much VOC mass might be
added and how much tracer mass might be lost simply by lowering the MSPFM into position
in the test interval, from 27.4 to 30.7 m (89.9 to 100.6 ft) bgs, and then immediately removing
it from well 68BR. In other words the effective deployment time of the MSPFM was zero.
This test was conducted on 6/4/15. The MSPFM was shipped to the site in a PVC tube and
was stored in the tube on-site until ready for use. Figure 2-4 shows the MSPFM used for
this test, which was about 1.2 m (4 ft) long, and the process of sample collection. Note the
norprene divider rings (Figure 2-4d) used to isolate sample intervals within the MSPFM and
induce horizontal flow while limiting vertical flow. As shown in Figure 2-4a, the work table
used during MSPFM sampling was covered with plastic sheeting, which was changed after
use, to prevent cross-contamination. Samples were collected directly from the MSPFM into
clean stainless steel bowls and homogenized with clean stainless steel spatulas. Pre-cleaned
wide mouth clear glass jars were filled to the top with sample, labeled, and stored on ice for
shipment to the laboratory at UF. After use, the bowls and spatulas were wiped clean with
paper towels, rinsed with distilled water as needed, and air dried.
2-7
-------
End cap
PVC Well Screen
Figure 2-4. MSPFM insertion/retrieval test.
a) MSPFM used in "insertion/retrieval" test, b) Removing the standard PFM from the PVC screen, c) Collecting
activated carbon from the PFM sample interval into a stainless steel bowl, d) Note gray norprene dividers
used to sub-divide the PFM into sample intervals and to limit vertical fluid movement, e) Sample of activated
carbon from the PFM ready to ship to the lab.
06/04/2015 I?-1
• v sSRfm.iS
Ob/OH/Pu15 12:0
A
2-8
-------
2.3.3 MSPFM deployment, retrieval, and sampling
The MSPFM was assembled and deployed on 6/5/15. The test interval was from 27.4 to 30.7 m (89.9 to 100.6 ft) bgs. The
MSPFM was deployed and retrieved at the same speed as the MSPFM used during the insertion/retrieval test so that the
loss and/or gain of mass data from the insertion/retrieval test could be applied to the data from the MSPFM. The MSPFM
consisted of three 1.2 m (4 ft) long segments. The three MSPFM segments were shipped to the site in PVC tubes and were
stored in the tubes on-site until ready for use. Figure 2-5 shows the sequence of MSPFM assembly and deployment.
After MSPFM retrieval on 6/23/15 a total of 20 samples, labeled SI through S20, were collected from the MSPFM by
homogenizing sorbent over fixed intervals, and then collecting a sub-sample for analysis. The samples spanned a 3.3 m
(10.7 ft) interval from 27.4 to 30.7 m (89.9 to 100.6 ft) bgs. A total of 5 samples, SI through S5, were collected from the
bottom MSPFM segment at intervals of 0.2 m (0.6 ft). The distance from sample S5, the last sample in the bottom MSPFM
segment and the first sample in the middle MSPFM segment, S6, was 0.49 m (1.6 ft). A total of 10 samples, S6 through
06/05/P0;l5 09:06' HM
06/0S/?0ISM08ElSa»ftl
ds/os/;ois II OS AH
66/05/20IS 11:01 KM
2-9
Figure 2-5. MSPFM assembly and deployment.
a) Lower and middle MSPFM segments being assembled, b) Redundant wire cable connection between two
MSPFM segments, c) Attaching the top cap to the MSPFM. d) MSPFM assembled and ready to deploy, total
length about 3.7 m (12 ft), e) Deploying the MSPFM in well 68BR. f) MSPFM suspended from PVC coupling,
g) Well cap in place, MSPFM deployed.
-------
S15, were collected from the middle MSPFM segment. These samples came from homogenizing the sorbent
over intervals of 0.1 m (0.3 ft). This MSPFM segment was centered on a point 29.0 m (95.1 ft) bgs just below
the fracture at 28.7 m (94 ft) bgs, and a finer sampling interval was used in an attempt to capture details of the
flowing fracture. The distance from sample S15, the last sample in the middle MSPFM segment and the first
sample in the top MSPFM segment was 0.49 m (1.6 ft). A totai of 5 samples, S16 through S20, were collected
from the top MSPFM segment based on homogenizing sorbent over intervals of 0.2 m (0.6 ft).
Figure 2-6 shows the process of MSPFM sample collection. Note the norprene divider rings used in the
MSPFM, Figure 2-6e, to help channel flow through the MSPFM and limit vertical flow. The sampling process
was identical to that described in Section 2.3.2 for the insertion/retrieval test.
Figure 2-6. MSPFM retrieval sampling.
a) MSPFM segment ready for sampling, b) MSPFM segment stored iri PVC shipping tube to reduce VOC loss before
sampling, c) Cutting the PFM mesh sock to collect sorbent material in segment, d) Collecting sample into stainless
steel mixing bowl, e) Note dividers between segments to limit vertical flow and to define sample intervals.
2-10
-------
2.4 Fractured Rock Passive Flux Meter
2.4.1 Description of the FRPFM
The FRPFM is an experimental system designed for deployment in a borehole completed in
rock. The FRPFM system consists of the following elements as shown in Figure 2-7.
• Three packers. The top and bottom packers are used to isolate the test zone occupied
by a middle packer in the borehole. The test zone is about 1 m (3 ft) long. The middle
packer is wrapped first in a green plastic mesh, then in sheets of activated carbon felt,
and finally an outer elastic fabric (nylon/spandex blend) sleeve dyed with turmeric
(hereafter referred to as the fabric sleeve). The mesh is used to induce a uniform
permeability through the activated carbon felt and fabric sleeve when compressed
against the borehole wall. Like the activated carbon in the MSPFM, the carbon felt is
impregnated with alcohols which elute at different rates. The carbon felt also absorbs
VOCs. The fabric sleeve is impregnated with turmeric dye, which fluoresces when
exposed to UV light. It is used to create an image of the flowing fractures on the
borehole wall.
• A weight and accelerometer are attached at the bottom of the packers. The weight helps
to deploy the FRPFM from the shield packer. The accelerometer is used to determine the
position of the FRPFM in the borehole relative to magnetic north during deployment.
• The shield consists of a stainless steel pipe, larger in diameter than the FRPFM, with a
packer at the top. The assembled FRPFM is placed inside the shield and is then held in
place by inflating the top and bottom FRPFM packers. The shield isolates the activated
carbon felt and fabric sleeve during deployment and retrieval. The FRPFM is also stored
and transported in the shield when not in use.
The diameter of this FRPFM system is constructed for deployment in a 0.2 m (6 in) diameter
borehole such as 68BR, but prototypes also exist for 0.1 m (4 in) boreholes.
2-11
-------
Figure 2-7. FRPFM components.
a) FRPFM arid shield components, b) FRPFM ready for attachment of activated carbon felt and fabric sleeve
prior to stowing in the shield for deployment.
FRPFM Top Packer
Shield
FRPFM Middle Packer
Covered with Green Mesh
Accelerometer Date Cable
FRPFM Bottom Packer
Shield Top Packer
Accelerometer
(bolted to the weight
before deployment)
Support Hardware
Weight
FRPFM
Shield
2-12
-------
2.4.2 FRPFM deployment, retrieval, and sampling
The FRPFM was prepared and deployed on 6/24/15 using the process illustrated in Figure 2-8, and
consisted of the following steps.
• The middle packer in the FRPFM was wrapped in green plastic mesh, four activated carbon felt
sheets, and then covered with the fabric sleeve. The activated carbon felt sheets were prepared at
UF by impregnating them with a suite of alcohol tracers, and were sealed in plastic bags and shipped
to the site in plastic containers. Likewise the fabric sleeve was also prepared at UF and transported to
the site in a sealed container.
• Immediately before installation of the FRPFM the activated carbon felt sheets were soaked in
distilled water in a plastic container for about 3 minutes to saturate them prior to deployment.
Pre-saturating them flushes trapped air from the pore space and promotes uniform permeability.
• A sample of the activated carbon felt was cut from each of the sheets before it was wrapped around
the FRPFM and placed in sample containers. These samples were analyzed to determine the initial,
or Cg, concentrations of VOCs and alcohols in the activated carbon felt. The value of Cg is used in
calculations to determine/ and qg.
• The carbon felt sheets were wrapped around the green plastic mesh, overlapped in the middle to
allow for expansion of the packer when it is inflated, and held in place temporarily with rubber
bands. The fabric sleeve was then installed over the carbon felt, rolled back to remove the rubber
bands from the felt, and then secured at either end using rubber bands.
• The assembled FRPFM was then slid inside the shield and the FRPFM packers were inflated to hold
the FRPFM in place and to isolate it from water in the borehole until it was in position and ready to
be deployed. In this way, the FRPFM is prevented from either losing alcohols or gaining VOC mass
while it is lowered into position.
• The shield/FRPFM was then lowered into position using the tripod. The shield was positioned above
the test zone so that when deployed the middle packer of the FRPFM was centered on the point
29.0 m (95.1 ft) bgs and the test interval was from 28.6 to 29.5 m (93.7 to 96.7 ft) bgs. Once in
position for deployment the top packer on the shield was inflated to hold it in position.
• The top and bottom packers on the FRPFM were then deflated to allow the FRPFM to be lowered
out of the shield and into position. In practice how quickly this process proceeds depends on the
transmissivity of the borehole below the shield packer. Based on previous experience deploying the
FRPFM in 68BR in 2012 (Hatfield, 2015), it was anticipated that the FRPFM deployment would be
very slow due to the time it takes for water displaced by the FRPFM to move into the fractures. To
speed up deployment, pressure on the shield packer was reduced temporarily to allow water below
the shield to bypass the shield as the FRPFM was deployed.
• Once in position the FRPFM core packer was inflated sealing the activated carbon felt and fabric
sleeve against the borehole wall. Then the FRPFM top and bottom packers were inflated to isolate
the interrogation zone from vertical flow. The shield was left in place with the shield packer inflated.
2-13
-------
Shield
Figure 2-8. FRPFM assembly and deployment.
a) Soaking activated carbon felt in distilled water, b) Preparing to attach activated carbon felt to the middle packer
iri the FRPFM. c) Wrapping the activated carbon felt around the middle packer, d) Activated carbon felt temporarily
held in place with rubber bands, e) Placing the fabric sleeve over the felt, f) Pulling back the fabric sleeve to remove
the rubber bands holding the felt in place, g) Fabric sleeve in place, h) Securing the fabric sleeve with rubber bands,
i) FRPFM stowed in the shield for deployment.
2-14
-------
The FRPFM was retrieved and sampled on 7/1/15 using the process illustrated in Figure 2-9, which
consisted of the following steps.
• All FRPFM packers were deflated and the unit was pulled up, using a line from the surface, into
the shield. The top and bottom packers were then re-inflated to hold the FRPFM in the shield and
the shield/FRPFM was raised to the surface. In this way, the FRPFM is prevented from either losing
alcohols or gaining VOC mass while it is raised to the surface.
• As the FRPFM was raised from the borehole several people were needed to manage the various
cables and tubing running to the FRPFM.
• The FRPFM was then removed from the shield and placed on a work table. The fabric sleeve was
removed and then the carbon felt sheets were removed and samples were collected.
In practice it was difficult to determine if the FRPFM was fully retrieved into the shield before it was
removed from the well. As shown in Figure 2-9a and 2-9b, a rock fragment was dislodged during
deflation of the core and wedged between the FRPFM and shield, which caused the fabric sleeve and
felt to be dragged down and bunch up at the bottom of the middle packer as the FRPFM was raised
into the shield. Both the fabric sleeve and felt were torn in places (Figure 2-9c and 2-9d) due to contact
with the rock fragment and borehole wall. Despite this problem the fabric sleeve was removed from the
FRPFM and inspected under UV light in a truck provided by the USGS. (See Figure 2-10.) The results of
this inspection were inconclusive with respect to evidence of flowing fractures. The fabric sleeve was
analyzed by UF for visual evidence of fracture flow under controlled conditions in their laboratory at the
university and the results are discussed in Section 3.
The carbon felt was removed from the FRPFM and laid out on the work table, covered with plastic
sheeting to prevent cross-contamination, and cut into sample strips (Figure 2-9e and 2-9f). The strips
were then placed into sample containers and stored on ice for transport and analysis at UF. A total of 19
samples were collected spanning the 0.9 m (3 ft) interval from 28.6 to 29.5 m (93.7 to 96.7 ft) bgs at a
spacing of approximately 6 cm (0.2 ft).
2-15
-------
-------
jr
-------
SECTION 3
Results and Synthesis
3.1 Existing borehole geophysical data review
Before reviewing the results of the BHD, MSPFM, and FRPFM the existing borehole data from 68BR were
reviewed to evaluate how the MSPFM or FRPFM would be deployed within the 68BR borehole. The rock
core collected by the USGS for this location is shown in Figure 3-1. Existing data from the 68BR borehole,
which are also typically collected at Superfund sites to characterize fractured bedrock hydrogeology, include
the following.
• Caliper
• Natural Gamma
• Optical televiewer (OTV)
• Acoustic televiewer (ATV)
• Stratigraphy
• Rock matrix sample results for TCE and cis-l,2-DCE
• Heat pulse flow meter data (ambient and pumped conditions)
• Head data from packer testing and calculated from the heat pulse flow meter (HPFM) data
• Transmissivity data from packer testing, calculated from HPFM, and a FLlJTe™ transmissivity profile
• Borehole fluid temperature and resistivity iogs under both pumped and ambient conditions
• VOC sampling results from packer sampling and long-term monitoring
The borehole geophysical logs were collected by the USGS in 2005 (Williams et al., 2007), the transmissivity
profile was collected by Flexible Liner Underground Technologies, LLC in June 2012 for the University of
Guelph (Parker, 2015), and the stratigraphy was developed by the USGS (Lacombe, 2000; Lacombe and
Burton, 2010). The rock matrix VOC sample results were reported in Goode et al. (2014) and provided by
the lead author. Note that because these data were collected by different investigators at different times
using different equipment the vertical resolution is assumed to be ± 0.3 m (± 1 ft).
Mas238
Figure 3-1. Rock
core from location
68BR collected by
the USGS.
The numbers on
the core indicate
the depth below
grade, and the
cores in this image
correspond to the
depth interval from
28 to 30 m (93 to
100 ft) below grade.
Ruler is calibrated in
decimal feet.
Image courtesy of
Pierre Lacombe,
USGS.
-------
These logs and other data sets are presented in Figure 3-2 and are typical of the investigative methods
deployed at EPA Superfund sites to characterize fractured bedrock hydrogeology. As detailed in Figure
3-2, these data provide multiple lines of evidence which indicate that the fracture at 28.7 m (94 ft) bgs
is transmissive, that significant concentrations of TCE and cis-l,2-DCE are present in the rock matrix
adjacent to the fracture (indicating exposure to contaminated groundwater and possibly dense non-
aqueous phase liquid (DNAPL) over time), and that the hydraulic head in this fracture is lower than the
head in the overlying shallow zone extending from the bottom of the casing to about 12 m (40 ft) bgs.
While the open borehole is an unnatural condition, the rock matrix VOC data indicate that there is a
vertical pathway for contaminated groundwater to reach this fracture. In a hypothetical site conceptual
model the fracture at 28.7 m (94 ft) bgs could be a pathway for offsite migration of contaminants. In
this context, the MSPFM or FRPFM would be deployed during the remedial investigation to evaluate the
mass flux in this fracture so that this information could be used in the remedial design.
3.2 Borehole Dilution Test
The groundwater conductivity data collected during the BHD are shown in Figure 3-3a, and were
analyzed using the method described in Pitrak et al., (2007). Along with the test zone dimensions, the
data was used to estimate qg for the test zone at 1.46 centimeters/day (cm/day). The test zone is 1.1 m
(3.6 ft) long and centered on a point 29.0 m (95.1 ft) bgs just below the fracture at 28.7 m (94 ft) bgs.
This estimate of qg was used to finalize the calculation of the duration of deployment of the MSPFM,
18 days, and the FRPFM, 7 days.
The BHD low flow sample results from the isolated test zone showed the concentrations of TCE and
cis-l,2-DCE increased from 0.34 mg/L and 0.88 mg/L, respectively, at the start of the purging to 1.16
mg/L and 4.59 mg/L, respectively after 2 hours of purging. After recirculation began and the BHD
started, the concentration of TCE dropped to 1.29 mg/L after 45 hours. In contrast, the cis-l,2-DCE
concentration leveled off and stayed at 1 mg/L for the duration of the test. Table 3-1 lists the results
which are plotted in Figure 3-3b.
Table 3-1 Low flow and BHD test sample results
Method
Sample
Elapsed Time
(hours)
cis-1,2-DCE
(mg/L)
TCE
(mg/L)
Low Flow
l
0
0.3
0.9
Low Flow
4
0.6
0.8
2.8
Low Flow
7
1.4
1.0
4.0
Low Flow
10
2.0
1.2
4.6
Borehole Dilution
1
00
00
1.0
2.7
Borehole Dilution
4
20.8
1.0
1.8
Borehole Dilution
7
26.8
1.0
1.6
Borehole Dilution
10
32.8
1.0
1.5
Borehole Dilution
13
44.8
1.0
1.3
mg/L = milligrams per liter
-------
Depth Caliper OTV MN ATV 16 Stratigraphy Matrix TCE Matrix cisDCE HPFM amb-5/25 Head Pack T Packer (m2/s) T HPFM (m2/s)
I I— I ) • —i I f-
RES(FL)
1ft:250ft 4 |NCH 15
GAM(NAT) 9041
H
1 (pg/g) 300 0 (pg/g) 25 -0,3 gal/min 0.3 87 Ft 97 1e-008 0.001 1e-006 0.001 58 DEG F 62 20 OHM-M 25
TCE 5/2009 DCE 5/2009 HPFM pump-5/25 Head HPFM T FLUTe m2/s TEMP 9721 RES(FL) 9721
CPS 1000
-H
O
0 pgrt. 25000 0 m^UQOOO-0.3 gal/min 0.3 87 Ft 97
Sim Amb
\ 1
-0.3 Gal/Min 0.3
Sim Pump
-0.3 Gal/Min 0.3
1e-Q06 0.001 57 DEG F 60 19 OHM-M 23
TEMP Pmp 16:45 RES(FL) Pmp 16 45
1 I
57 DEG F 60 19 OHM-M 23
TEMP Pmp 18:15 RES(FL) Pmp 18:15
I h-
57 DEG F 60 19 OHM-M 23
Lam165
Carb172
?
Mas 173
Cart>190
Masl9 ¦
Lam20'
Mos,7
Lam213
I
Lam227
V;is. V,
Lam244
,Carb246
Mas247
Larr25*
Cdfh/':.;
Figure 3-2. Well 68BR borehole geophysical data arid rock matrix VOC results.
a) Caliper log (red trace) showing fracture at 94 feet bgs. b) Fracture, dark sinusoidal band, shown on ATV. c)
Rock matrix sample results indicated by horizontal bars for TCE (red) arid cis-l,2-DCE (green) showing significant
concentrations, d) Groundwater sample results indicated by the vertical lines, the length of which indicates the
sampling interval, May 2009. e) Heat pulse flow meter (HPFM) data showing vertical flow of groundwater down, from
the zone at 40 feet, and exiting the borehole at the fracture at 94 feet bgs, note that below 94 feet the HPFM data
indicate essentially no vertical flow, f) Head data showing a downward gradient from the shallow to deep zones, g)
Packer test, HPFM, and FLUTe™ transmissivity data showing the fracture at 94 feet is trarismissive. h,i) Inflections at
94 feet in the fluid temperature and fluid resistivity logs indicating that fracture at 94 feet is transmissive. Borehole
geophysical data from Williams et al. (2007), and packer test data from Shapiro and Tiedeman (2005). Rock matrix
VOC data from Goode et al. (2014), FLUTe™ transmissivity profile data provided by Parker (2015). Groundwater
sample results from Geosyntec (2010).
3-3
-------
b)
5.0
4.5
4.0
s
3.5
£
— 3.0
c
o
1"
C 2.0
a
u
J is
1.0
0.5
0.0
Measured Data
Linear Trendline
y =-0.0001307x-0.02154
R! = 0.98
o -0,10
s -0.15
T3 -0.2C
t? -0 25
a
E -0.30
500 1000 1500 2000
Elapsed Time (min)
2500
3000
1
—UL
E
1 ' \
-A-TC
BHD Test Start
1
I I
-A
Y \
#
i
Low Flow i Borehole Dilution
15 20 25 30
Elapsed Time {hrj
Figure 3-3. BHD test results.
a) Measured conductivity data, normalized to the initial conductivity measurement (blue diamonds),
as a function of elapsed time from the start of the BHD test. Also shown is the trendline based on
a linear regression.
b) Aqueous contaminant concentrations from low flow sampling and BHD as a function of elapsed
time from the start of pumping the test zone prior to the start of the BHD test. The green dashed
line denotes the start of the BHD.
The observed increase in TCE and cis-l,2-DCE concentrations during low-flow sampling indicates
contaminated groundwater was being drawn into the pump from the test zone. Because the borehole
was open before the start of the BHD, groundwater from shallower depths flowed down and exited the
borehole at 28.7 m (94 ft) bgs. Therefore, the sample results probably reflect a mixture of groundwater.
During recirculation the TCE concentration dropped and cis-l,2-DCE concentration stabilized probably
reflecting ambient conditions in the zone.
Using Equation 1-2, ] for TCE in the BHD test interval was calculated as 18.8 milligrams/square meter/
day (mg/m2/day), based on qg = 1.46 cm/day and C .= 1.29 mg/L. Likewise/.for cis-l,2-DCE in the same
interval was calculated as 14.6 mg/m2/day, based on qg = 1.46 cm/day and Cp= 1.00 mg/L. These values
will be compared to the results from the MSPFM and FRPFM.
3-4
-------
3.3 Insertion/Retrieval test
Results from the MSPFM insertion/retrieval test were used to evaluate potential tracer loss and mass
sorption during insertion and retrieval of the device to the target depth. It should be noted that larger
deployment depths lead to larger potential tracer loss, while shorter depths (3 m/10 ft or less) lead to
minimal if any effect on observed values. For the measurements conducted in this study, it is estimated
that in the absence of results from the insertion/retrieval test, Darcy flux and contaminant flux from
the MSPFM test may have been overestimated by up to 8% and 3%, respectively. The results of the
insertion/retrieval test were used to estimate the MSPFM quantification limits as outlined below.
3.4 Modified Standard Passive Flux Meter
3.4.1 Quantification limit
Quantification limits for the MSPFM are limits below which measurements take on significant
uncertainty relative to higher measurements, and which take into account the effects of deployment
duration, water column depth, and the annular space between the MSPFM and borehole wall. The limits
for MSPFM will typically be lower for longer duration deployments, shallower water column depth, and
smaller annular water space. For the conditions of the test performed in 68BR (with duration of 18 days,
water column depth of 27 m (90 ft), and annular space of approximately 3 cm [1 in]), it was estimated
that the quantification limit for groundwater flux was approximately 0.5 cm/day, and the quantification
limit for contaminant flux was approximately 0.4 mg/m2/day.
3.4.2 Sample results
When evaluating the results of the MSPFM one must bear in mind the geophysical data discussed in
Section 3.1. In particular, the HPFM data, Figure 3-2e, and the head data, Figure 3-2f, show that under
open hole conditions, groundwater flows into the borehole in the interval above 12 m (40 ft) bgs, flows
downward at a rate of about 0.57 LPM (0.15 gallons per minute [gpm]) and exits the borehole at the
fracture at 28.7 m (94 ft) bgs. With the MSPFM deployed, the rate of downward water flow may be less,
due to blockage of the open borehole space by the MSPFM. Nonetheless, there is still the potential
for downward flow, and this means that a significant amount of contaminant mass may not be moving
through the MSPFM because ambient flow is into the fracture and away from the MSPFM. Likewise the
vertical flow component may dampen the groundwater flux measured by the MSPFM, which is designed
to measure horizontal groundwater flow. Lastly, the orientation of the MSPFM in the borehole is
unknown which means that it may be closer to the borehole wall in some places than others, which will
probably affect the tracer mass lost and the VOC mass absorbed.
A total of 20 samples were collected from the MSPFM spanning a 3.26 m (10.7 ft) interval from 27.4
to 30.7 m (89.9 to 100.6 ft) bgs. Sample spacing was 0.1 m (0.3 ft) in the middle interval centered on
the point 29.0 m (95.1 ft) bgs, which is comparable to the 6 cm (0.2 ft) spacing of the samples from the
FRPFM, and 0.2 m (0.6 ft) in the upper and lower MSPFM intervals. The results of the MSPFM sample
analysis are shown in Figure 3-4.
The groundwater flux averaged 2.14 cm/day over the interval sampled by the MSPFM. Values ranged
from 0.2 cm/day, at 30.3 m (99.4 ft) bgs, to 5.8 cm/day at 29.4 m (96.6 ft) bgs. The median value was 2
cm/day. Over the interval sampled by the FRPFM, from 28.6 to 29.5 m (93.7 to 96.7 ft) bgs, the MSPFM
average groundwater flux was 2.9 cm/day and ranged from 1.5 cm/day to 5.8 cm/day.
3-5
-------
Groundwater Flux (cm/day) Groundwater Flux (cm/day) Groundwater Flux (cm/day) Groundwater Flux (cm/day)
7 0 1
7 0 1
7 0 1
0)
o
t:
3
*/)
*D
c
3
2
e>
$
^o
0)
CO
Q.
Q>
Q
10 20 30 40 50 60 70 0 10 20 30 40 50 60 70 0 10 20 30 40 50 60 70 0 5 10 15
Mass Flux (mg/m2/day) TCE Flux (mg/mz/day) DCE Flux (mg/m2/day)
-•-TCE -A-DCE -~-Groundwater Flux
Flux Average Concentration
(mg/L)
Figure 3-4. MSPFM results. BHD interval, 93.3 to 96.9 feet bgs; FRPFM interval, 93.7 to 96.7 feet bgs.
The TCE mass flux averaged 28.23 mg/m2/day over the interval sampled by the MSPFM. The minimum TCE mass
flux was 13.3 mg/m2/day at 29.3 m (96 ft) bgs. The maximum TCE mass flux was 50.4 mg/m2/day at 27.4 m (89.9
ft) bgs. Over the interval sampled by the FRPFM, TCE mass flux from the MSPFM ranged from 13.2 mg/m2/day to
49.1 mg/m2/day and the average was 31.5 mg/m2/day. The highest TCE mass flux in this interval, 49.1 mg/m2/day,
was observed in the sample from 28.6 m (93.9 ft) bgs which is adjacent to the transmissive fracture observed at
28.7 m (94 ft) bgs. It could also reflect contaminated groundwater flowing down the borehole, partially through
the MSPFM, and exiting the borehole at this fracture. However, the groundwater flux profile is not consistent with
either of these explanations because the groundwater flux gradually increases from a depth of 27.4 to 29.0 m
(90 to 95 ft) bgs, without reflecting a peak groundwater flux near the transmissive fracture at 28.7 m (94 ft) bgs.
The cis-l,2-DCE and TCE mass flux follow a similar pattern but the cis-l,2-DCE values were higher and the average
was 38.1 mg/m2/day. The maximum cis-l,2-DCE mass flux, 64.4 mg/m2/day, was observed at 29.9 m (98.2 ft)
bgs. The minimum cis-l,2-DCE mass flux, 24.1 mg/m2/day, was observed at 28.0 m (91.7 ft) bgs. Over the interval
sampled by the FRPFM, cis-l,2-DCE mass flux from the MSPFM ranged from 28 to 56.7 mg/m2/day and the average
was 40.7 mg/m2/day. On the right side of Figure 3-4 the flux average contaminant concentrations are shown
graphically. The flux average contaminant concentration is an estimate of the groundwater concentration calculated
from the groundwater flux and mass flux. These data show that the highest flux average contaminant concentration
was present between 30.2 to 30.5 m (99.0 to 100.0 ft) bgs but that mass flux was low in this zone because of the
low groundwater flux. In fact, the groundwater flux was 0.2 cm/day at this location, which is below the estimated
quantification limit.
3-6
-------
3.5 Fractured Rock Passive Flux Meter
3.5.1 Quantification limit
Quantification limits for FRPFM are limits below which measurements take on significant uncertainty
relative to higher measurements, and which take into account deployment duration. Use of the FRPFM
shield avoids insertion and retrieval effects, therefore these effects do not impact the quantification
limits as they do for the MSPFM. For the conditions of the test performed in 68BR (duration of 7 days),
it was estimated that the technology quantification limit for groundwater flux was approximately
0.3 cm/day, and that the quantification limit for contaminant flux was approximately 0.2 mg/m2/day.
3.5.2 Sample Results
When evaluating the results of the FRPFM one must bear in mind the geophysical data discussed in
Section 3.1. In particular, the HPFM data, Figure 3-2e, and the hydraulic head data, Figure 3-2f, show that
under open-hole conditions, like those present before the FRPFM was fully deployed, groundwater flows
into the borehole in the interval above 12 m (40 ft) bgs, flows downward at a rate of about 0.57 LPM
(0.15 gpm) and exits the borehole at the fracture at 28.7 m (94 ft) bgs. However, unlike the MSPFM, the
FRPFM is equipped with packers to isolate the test interval from vertical groundwater movement in the
borehole. In particular, the top packer on the FRPFM should block the vertical flow in the borehole from
above the FRPFM. Together the top and bottom packers should isolate the test interval and maintain
conditions that minimize if not eliminate the influence of the open borehole. Moreover, one must also
bear in mind when evaluating the FRPFM results from this study that the FRPFM was damaged during
retrieval.
A total of 19 samples were collected spanning the 1 m (3 ft) interval from 28.6 to 29.5 m (93.7 to 96.7
ft) bgs at a spacing of 4.6 cm (0.15 ft), compared to 0.1 m (0.3 ft) sample spacing in the MSPFM over the
same interval. The results of the FRPFM sample analysis are represented graphically in Figure 3-5.
The groundwater flux averaged 2.7 cm/day over the interval sampled by the FRPFM. Values ranged from
1.3 cm/day, at 28.6 m (93.7 ft) bgs, to 3.5 cm/day at 29.5 m (96.7 ft) bgs. The median value was 2.9 cm/
day. Over the same FRPFM sampling interval, the average groundwater flux measured by the MSPFM
was 2.9 cm/day and ranged from 1.5 to 5.8 cm/day.
The TCE mass flux averaged 116 mg/m2/day over the interval sampled by the FRPFM. The minimum TCE
mass flux was 66.3 mg/m2/day at 28.6 m (93.7 ft) bgs. The maximum TCE mass flux was 215 mg/m2/day
at 28.7 m (94 ft) bgs. Over the interval sampled by the FRPFM, TCE mass flux from the MSPFM ranged
from 13.2 mg/m2/day to 49.1 mg/m2/day and the average was 31.5 mg/m2/day. The FRPFM cis-l,2-DCE
and TCE mass flux follow a similar pattern but the cis-l,2-DCE values were lower and the average was
68.2 mg/m2/day. The maximum cis-l,2-DCE mass flux, 104 mg/m2/day, was observed at 29.0 m (95.2 ft)
bgs. The minimum cis-l,2-DCE mass flux, 35.1 mg/m2/day, was observed at 28.6 m (93.7 ft) bgs. Over the
interval sampled by the FRPFM, cis-l,2-DCE mass flux from the MSPFM ranged from 28 mg/m2/day to
56.7 mg/m2/day and the average was 40.7 mg/m2/day.
3-7
-------
On the right side of Figure 3-5 the flux average contaminant concentrations are shown graphically.
These data follow the same pattern as the mass flux data due to the fact that groundwater flux is
relatively constant, averaging 2,7 cm/day, over the test interval. The highest flux average contaminant
concentration for TCE was 7.8 mg/L, detected at 28.7 m (94 ft) bgs, adjacent to the transmissive fracture
at this depth. The flux average contaminant concentration of cis-l,2-DCE was less variable than the TCE
concentration and peaked at 4.8 mg/L at 29.0 m (95.2 ft) bgs.
Groundwater Flux (cm/day) Groundwater Flux (cm/day) Groundwater Flux (cm/day) Groundwater Flux (cm/day)
01 23401 23401 23401 234
93.0
93.5
~ 94.0
5
o
at
m
95.0
95.5
a.
a>
a
96.0
96.5
97.0
a
X
co
00
-Q
cn
cri
oo
o
4—'
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l/)
0 100 200 300 0 100 200 300 0 100 200 300 0
Mass Flux (mg/m2/day) TCE Flux (mg/m2/day) DCE Flux (mg/m2/day)
-•-TCE -A-DCE -•-Groundwater Flux
10
Flux Average Concentration
(mg/L)
Figure 3-5. FRPFM Results.
BHD interval, 93.3 to 96.9 feet bgs; MSPFM interval, 89.9 to 100.6 feet bgs.
3-8
-------
3.5.3 Results of Analysis
of Fabric Sleeve for Fracture
Flow Information
The fabric sleeve from the
FRPFM was analyzed at the
UF iab to try to gather data
from it to determine fracture
frequency, to identify flowing
fractures, and to determine
groundwater flow direction.
Because the fabric sleeve was
damaged during retrieval, it
was not possible to evaluate
fracture frequency, flow, or flow
direction. Figure 3-6a shows
the image of the damaged
fabric sleeve. UF deployed the
FRPFM in the same zone in
2013 as part of another project
(Hatfield, 2015). The visual
results of that test are shown
in Figure 3-6b and can be
compared to the FRPFM sample
results from the current test
(Figure 3-6a). The visual results
from 2013 show flow, indicated
by the dark green traces on the
light green background, at the
fracture at 28.7 m (94 ft) bgs
as well as at smaller fractures,
which are less apparent on the
ATV and OTV, distributed in the
test interval below 28.7 m (94
ft). This is consistent with the
current sample results which
showed mass flux over the test
interval. The results from 2013
demonstrate one of the unique
capabilities of the FRPFM which
is to identify flowing fractures.
The results from 2013 indicated
a groundwater flow direction of
199 degrees (south-southwest).
a) EPA ORD RARE Project Deployment: NAWC Well 6SBR
Target Depth = 95.02 feet below ground surface (96.3 ft TOC), Nominal borehole diameter: 6 inches {15.24 cm)
Length of FRPFM sock image is approximately 108 cm = 3.54 feet
Width of FRPFM sock matches circumference of 6-inch (15.24 cm) diameter borehole
Deployed: 6/24/2015, Retrieved: 7/1/201S, Deployment duration: 7 days
Depth ATV
(ft-BGS) „
OTV
W 180* 270* 0» 0* 90* 180" 2 JO*
FRPFM
Visual Tracer
FRPFM
Fluxes
NOT!: Accurate determination of
compass dtrection w«s not possible
due to damage of visual dye sock
J "
I
£ H
0 SCO 200 M0
K>n Flux (moiVrr/day)
b) ESTCP Project, FRPFM Test O: NAWC Well 68BR (Hatfield 2015)
Target Depth = 95.12 feet below ground surface (96.5 ft TOC), Nominal borehole diameter: 6 inches (15.24 cm)
Length of FRPFM sock image is approximately 108 cm = 3.54 feet
Width of FRPFM sock matches circumference of 6-inch (15.24 cm) diameter borehole
Deployed: 10/11/2015, Retrieved: 10/17/2015, Deployment duration: 6 days
Depth
(ft-BGS) ,,
ATV
OTV
ISO8 270* 0* 0* 90* 1W 270® 0*
FRPFM
Visual Tracer
NOTE Cornpass directions for
visual dye Image are shifted to
maSch accelefometer reading.
FRPFM
Fluxes
SrowndwMtr F*uk
zS.—
Flow Direction
from Visual
Tracers
General Flow Direction =
199 degress (55 W)
NOTE: USGS, University of Guelph and University of Florida deployment and geophysical log depths vary within 1-foot of one another
with respect to borehole features. The ATV depth was adjusted to match the FRPFM depth measured In the field.
Figure 3-6. FRPFM groundwater flux comparison.
3-9
-------
3.6 Comparisons between methods
In comparing the results from the BHD, MSPFM, and FRPFM it is important to note that the three methods
all operate under different boundary conditions within the test zone. For all three approaches used to
estimate Darcy and contaminant fluxes, a flow convergence factor was used to account for the modified flow
field through the borehole devices (Klammler et al., 2007). The convergence factor for the BHD was 2.0, for
the FRPFM 1.9 and for the MSPFM 0.5, all calculated using estimated hydraulic conductivities for the aquifer
and components of each device. Borehole dilution testing, including low flow sampling, is performed in a
vertically isolated open-hole, the MSPFM is deployed in an open-hole, and the FRPFM is deployed under
vertically isolated closed-hole conditions. Therefore, no one technique is "right" as they each represent
different measures of groundwater flux and mass flux under different conditions that hopefully provide
comparable information. Previous work has shown good correlation between groundwater flux and mass
flux results between the BHD and FRPFM methods (Hatfield, 2015). In this previous study, the average
relative percent difference (RPD) of groundwater flux for 6 trials involving BHD and FRPFM tests in well 68BR
was -8%, while the average RPD of TCE mass flux in the same trials was -9%. However, comparisons made
here of the BHD and MSPFM results to the FRPFM results should be viewed bearing in mind that the FRPFM
was damaged during retrieval.
In addition, it is important to keep in mind that the instruments were deployed in series, for different
durations, and either under open-hole conditions or after the borehole had been open. Therefore natural
fluctuations in groundwater flux and VOC concentrations, and vertical movement of contaminated
groundwater from shallower parts of the borehole and exiting via the fracture at 28.7 m (94 ft) bgs may
also contribute to the observed differences in results. At the start of the BHD and FRPFM deployment,
groundwater quality in the test interval represented a mixture of groundwater from shallower zones and
test zone. In contrast, the borehole was open during the entire MSPFM deployment.
The results from the BHD, MSPFM, and FRPFM are compared in Table 3-2 and presented graphically in
Figure 3-7. Table 3-2 compares the results from these three methods and lists the RPDs calculated between
the results using the BHD results as the baseline, because this is the method most easily employed at the
present time at Superfund sites to measure groundwater flux and mass flux. In addition, the data from the
MSPFM is reported over the entire MSPFM interval, 27.4 to 30.7 m (89.9 to 100.6 ft) bgs, and also for the
interval sampled by the FRPFM (28.6 to 29.5 m [93.7 to 96.7 ft] bgs). This discussion will focus on the interval
sampled by the BHD (28.6 to 29.4 m [93.9 to 96.6 ft] bgs), the FRPFM, which are almost identical, and the
data for this same interval from the MSPFM.
The results show that the RPD between the groundwater flux measured with the BHD test, 1.5 cm/day,
and the average MSPFM (FRPFM interval), 2.6 cm/day, and average FRPFM, 2.7 cm/day, are 78% and 86%
respectively. These RPDs are larger than the average RPD of -8% based on six trials comparing BHD and
FRPFM results in well 68BR as reported in Hatfield (2015) from the previous study. It could be expected
that the BHD and the average FRPFM results would be more similar because both are closed-hole methods
isolating the same interval, while more difference is expected between these results and the average MSPFM
result because it is an open-hole method, and therefore subject to interference from vertical groundwater
flow. However, the average groundwater flux values from the MSPFM (FRPFM interval) and the FRPFM are
close at 2.6 cm/day and 2.7 cm/day, which suggests the MSPFM results were not significantly impacted
by vertical flow. Yet, the spatial patterns of groundwater flux as measured with the MSPFM and FRPFM
are not comparable, and the MSPFM results do not reflect the fracture at 28.7 m (94 ft) bgs. A detailed
diagnostic explanation for the differences in results cannot be offered at this time, in large part because
the true groundwater flux distribution during each test is unknown. Differences between the estimates of
groundwater flux may reflect differences between test methods, but actual changes in hydrologic conditions
between and during the tests cannot be ruled out.
3-10
-------
Table 3-2 Comparison of the BHD, MSPFM, and FRPFM results
Sample
Groundwater
cis-l,2-DCE
TCE
cis-l,2-DCE
TCE
Method
Interval
Flux
Concentration
Concentration
Mass Flux
Mass Flux
(feet)
(cm/day)
(mg/L)a
(mg/L)a
(mg/m2/day)b
(mg/m2/day)b
93.3
BHD
to
96.9
1.5
1.0
1.3
14.6
18.8
89.9
MSPFM
to
100.6
2.1
2.6
1.8
38.1
28.2
MSPFM
(FRPFM Interval)
93.9
to
96.6
2.6
1.5
1.2
40.7
31.5
93.7
FRPFM
to
96.7
2.7
2.6
4.3
68.2
115.7
Relative percent difference using BHD as the reference
BHD and MSPFM
N/Ac
47%
161%
39%
161%
50%
BHD and MSPFM
(FRPFM Interval)
N/A
78%
50%
-7%
179%
67%
BHD and FRPFM
N/A
86%
160%
231%
367%
515%
aThe concentration reported for the MSPFM and FRPFM are the average flux average contaminant concentration
calculated from the mass flux.
bThe mass flux values reported are the values calculated for the BHD and the average of the values calculated for
the indicated MSPFM and FRPFM test intervals.
CN/A - not applicable.
3-11
-------
Groundwater Flux (cm/day) Groundwater Flux (cm/day) Groundwater Flux (cm/day)
"O
C
3
O
k_
0
5
o
o
CO
150 0
101
300 0
MSPFM
Mass Flux (mg/m2/day)
MSPFM
TCE Flux (mg/m2/day)
MSPFM
DCE Flux {mg/m'/day}
Flux Average Contaminant
Concentration (mg/L)
Groundwater Flux (cm/day) Groundwater Flux (cm/day) Groundwater Flux (cm/day)
01 23456701 23456701 234567
88
89
90
91
£ 92
93
94
95
¦§ 96
CO
T3
C
D
O
k-
(D
Z
o
-------
The RPD between the cis-l,2-DCE concentration measured during the BHD, 1 mg/L, and the average
concentration calculated from the MSPFM (FRPFM interval), 1.5 mg/L, and FRPFM, 2.6 mg/L, are 50%
and 160% respectively. The values from the BHD and the MSPFM (FRPFM interval) are closer to one
another relative to the FRPFM result. As noted for the groundwater flux results, one would expect more
difference between the BHD and FRPFM results relative to the MSPFM result because the former two
are closed-hole methods while the latter is an open-hole method and therefore subject to interference
from vertical groundwater flow. Evidence for this was observed during low flow sampling before the BHD
test when the cis-l,2-DCE concentration rose from 0.34 mg/L at the start of sampling to 1.16 mg/L just
before the start of the BHD (Section 3.2). Likewise, greater similarity could be expected between the
BHD and the FRPFM results because both are closed-hole methods isolating the same interval. Instead
the RPD is 160% and the FRPFM result is more than twice the BHD value.
The RPD between the TCE concentration measured during the BHD, 1.3 mg/L, and the average calculated
from the MSPFM (FRPFM interval) flux average concentration, 1.2 mg/L, and FRPFM flux average
concentration, 4.3 mg/L, are -7% and 231% respectively. Again, the values from the BHD and the MSPFM
(FRPFM interval) are close, respectively, at 1.3 mg/L and 1.2 mg/L, while the FRPFM result indicates a
greater difference. Evidence for potential impacts on the MSPFM test due to vertical flow was observed
during low flow sampling before the BHD when the TCE concentration rose from 0.88 mg/L at the start
of sampling to 4.59 mg/L just before the start of the BHD (Section 3.2). But this does not explain the
similarity between the BHD and MSPFM results, as well as the relative difference compared to these in
the FRPFM result.
The RPD between the cis-l,2-DCE mass flux based on the BHD, 14.6 mg/m2/day, and the calculated
averages from the MSPFM (FRPFM interval), 40.7 mg/m2/day, and FRPFM, 68.2 mg/m2/day, are 179%
and 367% respectively. Similarly, the RPD between the TCE mass flux based on the BHD test, 18.8 mg/
m2/day, and the calculated averages from the MSPFM (FRPFM interval), 31.5 mg/m2/day, and FRPFM,
116 mg/m2/day, are 67% and 515% respectively. In both cases, the BHD gave the lowest estimates and
the FRPFM gave the highest estimates of contaminant flux. Moreover, the spatial distributions of cis-
1,2-DCE and TCE contaminant flux estimates based on the MSPFM and FRPFM measurements are not
very similar. Across the board the RPD of the FRPFM is greater than that of the MSPFM. In the MSPFM
the sorbent media is never in contact with the borehole wall and is probably only exposed to VOCs in the
dissolved phase. In contrast, the design of the FRPFM results in more direct contact of the sorbent media
and the borehole wall, exposing it not only to dissolved phase VOCs in the fracture, but also possibly
to DNAPLs or dissolved phase VOCs in the rock matrix, and sorbed VOCs on the rock matrix. The rock
matrix sample results, see Figure 3-2c, show the cis-l,2-DCE and TCE were both detected in the rock
matrix in the FRPFM sampling interval. However, comparable differences between the BHD and FRPFM
results were not observed during the previous study (Hatfield, 2015) that involved comparisons of
these methods in well 68BR. As noted before, the groundwater flux calculated with the MSPFM (FRPFM
interval) and the FRPFM are similar suggesting that contact with the borehole wall, if it is a factor, may
not make a significant difference in the loss of tracers.
As noted in the case of groundwater flux discussed above, the exact reason for the differences in
estimates of flux-average concentration and contaminant flux are unknown at this time. Most likely, the
differences stem from differences in measurement methods between the three techniques, but natural
variability in conditions during the tests may also be a factor. Moreover, damage to the FRPFM during
retrieval may also play a factor in the results obtained. Additional research is needed to better evaluate
method accuracy, such as laboratory tests in which the true contaminant flux distribution is known.
3-13
-------
3.7 Comparisons to common borehole geophysical methods
For comparison, the BHD, MSPFM, arid FRPFM groundwater flux and mass flux data are posted with the
geophysical logs from well 68BR on Figure 3-8. The range of borehole geophysical toois discussed in Section 3.1
provide useful, necessary, and high quality data on the physical characteristics of the borehole but do not provide
groundwater flux or mass flux data. Currently, borehole dilution testing, as conducted during this project, is the
most common method for estimating groundwater flux and mass flux in fractured rock boreholes. The MSPFM
and FRPFM can also be used to estimate groundwater flux and mass flux, but like the BHD, the geophysical logging
tools described in Section 3.1 must first be used to characterize the borehole and provide the data needed to
select targets for deployment of the MSPFM or FRPFM. Therefore, the MSPFM and FRPFM complement rather
than replace existing tools.
Depth
1ft:25ft
Stratigraphy
BHD GF
0 cm/day 7 0 250 0 150 0 iigiL 25000 0 mq/l 10000 -0.3 gal/min 0.3 87
MSPFM GF FRPFM TCE MF FRPFM DCE MF Sim Amb
I Q 1 • 1 # i I 1
0 cm/day 7 0
FRPFM GF
0 cm/day 7
Feature
\ H
BHD TCE MF BHD DCE MF Matrix TCE Matrix cisDCE HPFM amb-5/25 Head Pack
I I 1 \ •
0 250 0 150 1 (pg/g)300 0 (pg/g) 25 -0.3 gal/min 0.3 87 Ft 97 1e-006
MSPFM TCE MFMSPFM DCE MF TCE 5/2009 DCE 5/2009 HPFM pump-5/25 Head HPFM
-I O 1 e 1 1 rrrrj O
T HPFM (m2/s) T Packer (m2/s) T FLUTe m2/s
0.001 1 e-008 0.001 1e-006 0.001
250 0
150
d, e
-0.3 Gal/Min 0.3
Sim Pump
-0.3 Gal/Min 0.3
Ft
g
97
0
0
0
Figure 3-8. Comparison of borehole geophysical and sample data and BHD, MSPFM, and FRPFM results.
a) FRPFM and MSPFM groundwater flux (GF) data, cm/day, overlaid on the ATV log. b) FRPFM and MSPFM TCE mass
flux (MF)data, mg/m2/day. c) FRPFM and MSPFM eis 1.2 DCE mass flux data, mg/m2/day. d) Rock matrix sample results
for TCE and cis-l,2-DCE, e) Groundwater sample results, May 2009. f) HPFM data showing vertical down flow exiting
the borehole at the fracture at 94 feet bgs. g) Head data showing a downward gradient from the shallow to deep zones
(see Figure 3-2). h) Packer test, HPFM, and FLUTe™ transmissivity data showing the fracture at 94 feet is transmissive.
Borehole geophysical data from Williams et al. (2007), and packer test data from Shapiro and Tiedemari (2005). Rock
matrix VOC data from Goode et al. 2014. FLUTe™ transmissivity profile data provided by Parker (2015). Groundwater
sample results, Geosyntec, 2010.
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As pointed out by Hatfield (2015), due to the high resolution nature of the FRPFM technology, its
optimum application is characterizing targeted borehole depth intervals and not screening conditions
over an entire borehole. The FRPFM used in this study is designed to investigate aim (3.28 ft) interval.
Changing the sample interval would require rebuilding the tool or designing a new tool with the ability
to vary the sampling interval. As a practical matter the existing FRPFM is an experimental tool designed
to test the concept, materials, and procedures and collect data to validate the technology. Due to the
complexity of preparing, deploying, retrieving, and sampling the FRPFM it would not be practical to
employ it, in its present form, at a large number of Superfund sites. In contrast, the length of the MSPFM
can be adjusted relatively easily and is easier to deploy, retrieve and sample. The MSPFM is also less
vulnerable to damage than the FRPFM, and is much more similar to the commercially available, standard
PFM technology. However, because the MSPFM is not equipped with packers it must be deployed in an
open borehole where vertical fluid movement during deployment could complicate data interpretation
and potentially allow cross-contamination between different zones in the borehole. Therefore, the
performance of the MSPFM could be improved if a way can be found to limit vertical fluid movement
in the annular space while the MSPFM is deployed. One way this might be accomplished would be by
adapting the flexible petal technology used to channel flow through a heat pulse flow meter to the
MSPFM (Figure 3-9).
Flexible Baffle on Heat
Pulse Flow Meter
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iffri
SECTION 4
Conclusions and
Recommendations
This section summarizes the methods
for evaluating groundwater flux and
contaminant mass flux within rock
boreholes which were evaluated during
this project and provides conclusions and
recommendations regarding each method.
The three methods tested had specific
logistical issues related to preparation,
equipment complexity, deployment,
retrieval, sampling, and data analysis
required to estimate groundwater flux and
contaminant mass flux, in addition, to use
any of these methods the borehole must
be opened to at least deploy equipment,
such that vertical fluid movement may
occur. This needs to be considered in
the planning of the work and in the
interpretation of the data.
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4.1 Borehole Dilution Test
During this project a BHD test was successfully used to estimate groundwater flux and mass flux.
Results from the BHD test served as a basis of comparison to the MSPFM and FRPFM results, because
the former is currently the more commonly applied method relative to the latter two. Moreover, BHD
results were used to calculate the deployment time for the MSPFM and FRPFM. It may be possible in
other applications to estimate deployment duration for the MSPFM and FRPFM technologies from other
site-specific characterization data, thus eliminating the need to conduct a BHD test in conjunction with
MSPFM or FRPFM tests. However, this option currently remains untested and should be explored in
future work.
Executing a BHD test requires a straddle packer system set up to recirculate groundwater in the
borehole. For the configuration used in this project, it also required above ground plumbing and
instrumentation, which necessitates security and weather protection considerations. Conducting a BHD
test can be completed by personnel experienced with the procedure and with access to the appropriate
equipment. Such personnel should also be familiar with typical field sampling techniques and protocols
to ensure, for example, that water specific conductivity data and VOC sampling are completed properly.
Other methods for conducting borehole dilution tests, such as those discussed in Section 1.3, are
available but are typically done in open boreholes and so are subject to inaccuracies when significant
vertical flow is observed.
The BHD method provides an integrated measure of groundwater flux across the entire test interval.
The data resolution is a function of the length of the interval between the packers. It does not provide
information at higher resolution in and around transmissive fractures within the interrogated interval.
In order to calculate mass flux, the groundwater flux is multiplied by the contaminant concentrations.
As shown during this test however, contaminant concentrations varied significantly during the low-
flow sampling. It is important that the concentrations used in the calculation of contaminant mass
flux are representative of the concentrations associated with the transmissive zone or fracture(s) in
the interrogated interval. In the case when concentrations vary, judgement may be needed in the
interpretation of the data. On the other hand, concentration-time series information both before and
after the start of the BHD provide data that can be used to make qualitative assessments about the
relative proximity of the sampling location to sources of higher concentration.
Towards this end, one limitation of the system used during this test is that it was not equipped with
pressure transducers above, between, and below the packers. It is recommended that pressure
transducers be used to collect water level data for use in determining the quality of the seal between
the packer and borehole wall. One problem with packers is that flow may simply "short circuit" around
the packer via the formation. Water level data can be used to help assess if this is occurring. Knowing
whether or not the test interval is isolated from the interval above and below is necessary for a complete
interpretation of the VOC sample and borehole dilution data. In this case, the decrease in depth to water
observed during the BHD test (Table 2-2) suggests that the test interval was isolated.
4-2
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4.2 MSPFM
The MSPFM, compared to the FRPFM, was easier to prepare, deploy, retrieve, and sample. For
example, the MSPFM is contained inside a well screen so it is protected from the borehole wall
and less likely to be damaged during retrieval than the FRPFM. However, at the present time, an
initial insertion/retrieval test is required to correct the tracer-based groundwater flux and mass
flux estimates to account for tracer losses and contaminant mass loading onto the sorbent during
deployment and retrieval. An insertion/retrieval test is not required for the FRPFM because it is
deployed and retrieved inside a shield. The main advantage of the MSPFM is that it is a modified
version of the commercially available PFM that is already in use. The main disadvantage of the
MSPFM is that it may underestimate groundwater flux and contaminant mass flux when deployed
in an open borehole subject to influence from vertical flow. Moreover, deployment in an open
borehole may not be acceptable at sites because vertical fluid movement in the open borehole could
cross-contaminate different zones. It is also a patented technology owned by UF. An improvement
to the existing MSPFM design is a modification that would prevent vertical fluid flow in the annular
space between the MSPFM and borehole wall during deployment. An example of a baffle used in a
borehole geophysical logging tool for this purpose is discussed in Section 3.7. In addition, unlike the
FRPFM, the MSPFM does not provide information on groundwater flow direction or flow in specific
fractures. Furthermore, like the BHD and FRPFM, a borehole logging program needs to be undertaken
in a borehole before deciding where to deploy the MSPFM. Comparisons of the spatial distributions
of groundwater flux and contaminant mass flux between the MSPFM and FRPFM as measured in
this project indicate more research is needed to further assess the accuracy of and confidence in
measurements of spatial distributions. Controlled experiments in which the true distribution is
known would be helpful in this regard.
4.3 FRPFM
The FRPFM offers a unique combination of capabilities including the following for active or flowing
fractures: (1) location along the borehole; (2) number; (3) individual fracture orientations in terms
of strike, dip, and orientation of dip (direction of falling dip, e.g., SW); (4) cumulative groundwater
flux; and (5) groundwater flow direction. Fracture characteristics (1) through (3) can be obtained
through existing borehole imaging technologies (as long as those fractures can be resolved);
however, these commercially available technologies cannot measure the magnitude or direction of
fracture flow. Further analytical analysis of the FRPFM internal sorbent layer at indicated locations
of active fractures yields: (1) additional estimates of cumulative groundwater flux in fractures; and
(2) cumulative contaminant flux in those fractures. Thus, the in situ measurements of direction and
magnitude of water and contaminant fluxes in active fractures are given by the FRPFM alone.
However, the FRPFM, compared to the MSPFM and BHD, was the most complex method to prepare,
deploy, retrieve, and sample. Due to the complexity of preparing, deploying, and sampling the
FRPFM and due to the fact the patent holder (UF) currently needs to provide these services, it is not
practical to use the FRPFM at a large number of sites at this time. At present, its best use would be
those applications where high resolution data is needed over short intervals. The FRPFM does not
require an insertion/retrieval test because it is deployed and retrieved inside a shield. However, the
FRPFM is fragile and if there are problems retracting it into the shield, as happened during this study
due to rock falling in from the borehole wall, then valuable data may be lost and data interpretation
complicated. Furthermore, as with the BHD and MSPFM, a borehole logging program needs to be
undertaken in a borehole before deciding where to deploy the FRPFM. Further development of the
FRPFM technology may result in a more widely applicable technology. For example, combining this
technology with flexible underground liner technology may simplify deployment and retrieval.
4-3
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SECTION 5
References
Acar, 0., H. Klammler, K. Hatfield, M.A. Newman, M.D. Annable, J. Cho, B.L. Parker, J.A. Cherry, P. Pehme,
P. Quinn, and R. Kroecker. 2013. A stochastic model for estimating groundwater and contaminant
discharges from fractured rock passive flux meter measurements. Water Resources Research, 49,
1277-1291, doi: 10.1002/wrcr.20109.
Cherry, J.A., B.L. Parker and C. Keller. 2007. A new depth-discrete multilevel monitoring approach for
fractured rock. Ground Water Monitoring & Remediation, 27(2): 57-70.
EPA 2015. Quality Assurance Project Plan: Measuring contaminant mass flux and groundwater velocity
in a fractured rock aquifer using passive flux meters. EPA Region 2, Emergency and Remedial Response
Division, New York.
Geosyntec 2010. Final Draft Report Bioaugmentation Pilot Study Former NAWC Trenton Site West
Trenton, NJ. Project Number JR0021. Prepared for ECOR Solutions, Inc., 1075 Andrew Drive, Suite 1,
West Chester, PA. May.
Goode, D.J., T.E. Imbrigiotta, and P. J. Lacombe. 2014. High-resolution delineation of chlorinated
volatile organic compounds in a dipping, fractured mudstone: Depth- and strata-dependent spatial
variability from rock-core sampling. Journal of Contaminant Hydrology, v. 171, p. 1-11, doi:10.1016/j.
jconhyd.2014.10.005.
Hatfield, Kirk; Rao, P. Suresh C.; Annable, Michael D.; Campbell, Timothy J., Device and method for
measuring fluid and solute fluxes in flow systems. US Patent (6,401,547). 2002.
Hatfield, K., M. Annable, J. Cho, P.S.C. Rao, and H. Klammler. 2004. A direct passive method for measuring
water and contaminant fluxes in porous media. Journal of Contaminant Hydrology 75, p. 155- 181.
Hatfield, K., 2015. Final Report: Demonstration and Validation of a Fractured Rock Passive Flux Meter
(FRPFM). ESTCP Project Number: ER-200831.
ITRC (Interstate Technology & Regulatory Council). 2010. Use and measurement of mass flux and mass
discharge. MASSFLUX-1. Washington, D.C.: Interstate Technology & Regulatory Council, Integrated DNAPL
Site Strategy Team, www.itrcweb.org.
Klammler, H., K. Hatfield, M.D. Annable, E. Agyei, B.L. Parker, J.A. Cherry, and P.S.C. Rao. 2007. General
analytical treatment of the flow field relevant to the interpretation of passive fluxmeter measurements.
Water Resour. Res., 43, W04407, doi:10.1029/2005WR004718.
Klammler, Harald Rene; Hatfield, Kirk; Annable, Michael D.; Cherry, John Anthony; Parker. Beth Louise.,
Device and method for measuring fluid fluxes, solute fluxes and fracture parameters in fracture flow
systems. US Patent (7,334,486). 2008.
Kolditz, O., 2002. Computational Methods in Environmental Fluid Mechanics, Springer-Verlag, Berlin,
378 pgs.
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Lacombe, P.J., 2000. Hydrogeologic framework, water levels and trichloroethylene contamination,
Naval Air Warfare Center, West Trenton, New Jersey, 1993-97: U.S. Geological Survey Water-Resources
Investigations Report 98-4167, 139 pgs.
Lacombe, P.J., 2002. Ground-water levels and potentiometric surfaces, Naval Air Warfare Center, West
Trenton, New Jersey, 2000: U.S. Geological Survey Water-Resources Investigations Report 01-4197,
38 pgs.
Lacombe, P. J. and W. C. Burton. 2010. Hydrogeologic framework of fractured sedimentary rock, Newark
Basin, New Jersey. Groundwater Monitoring and Remediation. Vol. 30, No. 2. p. 35-45. doi: 10.1111/
jl745-6592.2010.001275.x.
Michalski, A. and G. M. Klepp. 1990. Characterization of transmissive fractures by simple tracing of in-
well flow. Ground Water. Vol. 28, No. 2. March-April, p. 191-198.
Parker, B. L., 2015. Personal communication. FLUTe™ transmissivity profile collected on June 21, 2012
from well 68BR at the former Naval Air Warfare Center in West Trenton, NJ by Flexible Underground
Liner Technology for the University of Guelph.
Pehme, P.E., B. L. Parker, J. A. Cherry, D. Blohm. 2014. Detailed measurement of the magnitude and
orientation of thermal gradients in lined boreholes for characterizing groundwater flow in fractured rock.
J. Hydrology (484), 1-15. http://dx.doi.Org/10.1016/j.jhydrol.2014.03.015.
Pitrak, M. S. Mares, and M. Kobr. 2007. A simple borehole dilution technique in measuring horizontal
ground water flow. Ground Water, Vol. 45, No. 1, January-February, p. 89-92.
Shapiro, Allen, and Tiedeman, Claire, USGS, written communication. 2005.
Tiedeman, C., P. J. Lacombe, D. J. Goode. 2010. Multiple well-shutdown tests and site-scale flow
simulation in fractured rocks. Ground Water. Vol. 48, No. 3. May-June, p. 401-415.
Williams, J.H., P.J. Lacombe, C. D. Johnson, and F. L. Pail let. 2007. Cross-borehole flow tests and insights
into hydraulic connections in fractured mudstone and sandstone, in Proceedings of the Symposium
on the Application of Geophysics to Engineering and Environmental Problems (SAGEEP 2007), Denver,
Colorado, April 1-5, 2007: Denver, Colo., Environmental and Engineering Geophysical Society, p. 1,140-
1,152 (CD-ROM).
Wilson, J.T., W.A. Mandell, F.L. Paillet, E. R. Bayless, R.T. Hanson, P.M. Kearl, W.B. Kerfoot, M.W.
Newhouse, and W.H. Pedler. 2001. An evaluation of borehole flowmeters used to measure horizontal
ground-water flow in limestones of Indiana, Kentucky, and Tennessee, 1999: U.S. Geological Survey
Water-Resources Investigations Report 01-4139, 129 pgs.
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APPENDIX
Data Quality Assurance and Quality Control
As required by EPA's quality assurance policy, a QAPP was prepared and approved for this project prior
to collection of data and implemented without significant deviations. A QAPP describes the technical
and quality assurance/quality control (QA/QC) activities of an environmental research project that is
implemented to ensure that the results will satisfy the intended use of the data.
Secondary data (i.e., data taken from other published reports) used in this project was collected as
part of Environmental Security Technology Certification Program (ESTCP) funded research projects.
These projects require written quality assurance procedures in their demonstration plans, and these
procedures were deemed appropriate and acceptable for the research goals of this project.
Groundwater samples collected during the borehole dilution test were analyzed at a UF laboratory for
cis-l,2-DCE and TCE concentrations using a Shimadzu single quadrupole gas chromatography/mass
spectrometer (GCMS-QP2010 SE) with an Evolution Purge and Trap Concentrator. Analytical quality
control included positive controls (calibration checks and matrix spikes), negative controls (blanks),
and duplicates. Data quality acceptance was determined by the UF principle investigators for the
project using their laboratory's documented acceptance criteria. Analytical data used in this report
satisfied those QA/QC requirements.
Extracts from MSPFM and FRPFM sorbent samples were analyzed at a UF laboratory for alcohol
(methanol, ethanol, isopropyl alcohol, tert-butyl alcohol, and 2,4-dimethyl-3-pentanol) and volatile
organic compound (cis-l,2-DCE and TCE) concentrations. The analytical method used a Perkin Elmer
Autosystem gas chromatography with a flame-ionization detector. Analytical quality control included
positive controls (calibration checks and matrix spikes), negative controls (blanks), and duplicates.
Data quality acceptance was determined by the UF principle investigators for the project using their
laboratory's documented acceptance criteria. Analytical data used in this report satisfied those
QA/QC requirements.
A-l
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United States
Environmental Protection
Agency
Office of Research and Development
Washington, DC 20460
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