United States Office of Research and EPA/600/R-00/062
Environmental Protection Development August 2000
Agency Washington, D.C. 20460
vvEPA Environmental Technology
Verification Report
Groundwater Sampling
Technologies
QED Environmental Systems,
Inc.
Well Wizard® Dedicated Sampling
System
Sandia
National
Laboratories
ETV ETV ET
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THE ENVIRONMENTAL TECHNOLOGY VERIFICATION
PROGRAM
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ETV JOINT VERIFICATION STATEMENT
TECHNOLOGY TYPE: GROUNDWATER SAMPLING TECHNOLOGIES
APPLICATION: VOC-CONTAMINATED WATER SAMPLING
TECHNOLOGY NAME: Well Wizard Dedicated Sampling System — Models T1200M
and T1250
COMPANY: QED Environmental Systems Inc.
ADDRESS: 6095 Jackson Road PHONE: (800) 624-2026
Ann Arbor, MI 48106 FAX: (313) 995-1170
WEBSITE: www.micropurge.com
EMAIL: info@qedenv.com
The U.S. Environmental Protection Agency (EPA) has created the Environmental Technology
Verification Program (ETV) to facilitate the deployment of innovative or improved environmental
technologies through performance verification and dissemination of information. The goal of the ETV
Program is to further environmental protection by substantially accelerating the acceptance and use of
improved and cost-effective technologies. ETV seeks to achieve this goal by providing high-quality,
peer-reviewed data on technology performance to those involved in the design, distribution, financing,
permitting, purchase, and use of environmental technologies.
ETV works in partnership with recognized standards and testing organizations and stakeholder groups
consisting of regulators, buyers, and vendor organizations, with the full participation of individual
technology developers. The program evaluates the performance of innovative technologies by
developing test plans that are responsive to the needs of stakeholders, conducting field or laboratory tests
(as appropriate), collecting and analyzing data, and preparing peer-reviewed reports. All evaluations are
conducted in accordance with rigorous quality assurance protocols to ensure that data of known and
adequate quality are generated and that the results are defensible.
The Site Characterization and Monitoring Technologies Pilot, one of 12 technology areas under ETV, is
administered by EPA's National Exposure Research Laboratory. Sandia National Laboratories, a
Department of Energy laboratory, is one of the verification testing organizations within the ETV Site
Characterization and Monitoring Pilot. Sandia collaborated with personnel from the US Geological
Survey (USGS) to conduct a verification study of groundwater sampling technologies. This verification
statement provides a summary of the results from a verification test of the Well Wizard bladder pumps
and pneumatic controller manufactured by QED Environmental Systems Inc.
EPA-VS-SCM-41 The accompanying notice is an integral part of this verification statement. August 2000
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DEMONSTRATION DESCRIPTION
In August 1999, the performance of six groundwater sampling devices was evaluated at the US
Geological Survey Hydrological Instrumentation Facility at the National Aeronautics and Space
Administration (NASA) Stennis Space Center in southwestern Mississippi. Each technology was
independently evaluated in order to assess its performance in the collection of volatile organic
compound- (VOC) contaminated water.
The verification test design incorporated the use of a 5-inch-diameter, 100-foot standpipe at the USGS
facility. The standpipe, serving as an "aboveground" well, was filled with tap water spiked with various
concentration levels of six target volatile organic compounds. The target compounds (1,2-
dichloroethane, 1,1-dichloroethene, trichloroethene, benzene, 1,1,2-trichloroethane, and
tetrachloroethene) were chosen to represent the range of VOC volatility likely to be encountered in
normal sampler use. Water sampling ports along the exterior of the standpipe were used to collect
reference samples at the same time that groundwater sampling technologies collected samples from the
interior of the pipe. A total of seven trials were carried out at the standpipe. The trials included the
collection of low (-20 |Jg/L) and high (-200 |Jg/L) concentrations of the six target VOCs in water at
sampler depths ranging from 17 to 91 feet. A blank sampling trial and an optional "clean-through-dirty"
test were also included in the test matrix. The "clean-through-dirty" test was included to investigate the
potential of contaminant carryover as a sampler is lowered through a "dirty" (high VOC concentration)
layer of water in order to sample an underlying "clean" (low VOC concentration) layer. The test was
optional for samplers such as the Well Wizard dedicated sampling system, which is designed for
permanent deployment in a single monitoring well.
The standpipe trials were supplemented with additional trials at groundwater monitoring wells in the
vicinity of VOC-contaminated groundwater at the NASA Stennis facility. The sampling devices were
deployed in a number of 2-inch and 4-inch wells, along with colocated submersible electric gear pumps
as reference samplers. The principal contaminant at the onsite monitoring wells was trichloroethene.
The onsite monitoring provided an opportunity to observe the operation of the sampling system under
typical field-use conditions.
All technology and reference samples were analyzed by two identical field-portable gas chromatograph-
mass spectrometer (GC/MS) systems that were located at the test site during the verification tests. The
GC/MS analytical method used was a variation of EPA Method 8260 purge-and-trap GC/MS,
incorporating a headspace sampling system in lieu of a purge-and-trap unit. The overall performance of
the groundwater sampling technologies was assessed by evaluating sampler precision and comparability
with reference samples. Other logistical aspects of field deployment and potential applications of the
technology were also considered in the evaluation.
Details of the demonstration, including an evaluation of the sampler's performance, may be found in the
report entitled Environmental Technology Verification Report: QED Environmental Systems Inc. Well
Wizard Dedicated Sampling System, EPA/600/R-00/062.
TECHNOLOGY DESCRIPTION
The Well Wizard is a bladder pump consisting of an internal flexible bladder that is positioned within a
rigid stainless steel pump body. The inner bladder is equipped with one-way inlet and outlet valves and
passively fills with water when the pump is at depth in the well as a result of the hydrostatic pressure
exerted by the surrounding water column. Following the fill cycle, compressed air or nitrogen from a
cylinder or compressor at the wellhead is driven down to the pump through tubing to compress the bladder,
thus driving the water sample up to the surface through a second tubing line. The pumping sequence
consists of repeated fill-compress cycles, using a pneumatic controller positioned at the wellhead. The
controller is used to vary the duration and frequency of the fill-compress cycles in order to deliver the
EPA-VS-SCM-41 The accompanying notice is an integral part of this verification statement. August 2000
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desired sample flow rate at the wellhead. The bladder design offers the advantage of minimizing sample
turbulence, which can result in loss of VOCs in the sample, as well as eliminating contact of the water
sample with the compressed air or nitrogen used to lift the sample to the surface.
QED Environmental offers a complete line of bladder pumps manufactured with various materials. Two
pumps tested during this evaluation were the Model T1220M and the T1250. These two pumps were
essentially the same in design and construction materials with differences only in pump length—the Model
1220 was 1.04 m in length and the 1250 was 0.38 m in length. Both pumps use polytetrafluoroethylene
(Teflon) for the bladder material and 316 stainless steel for the pump body, fittings, and intake screen. The
external diameter of both pumps was 3.8 cm (1.5 inches). The pump intake stainless steel screen mesh size
was 0.25 mm (0.01 inch). Both pumps have a maximum lift capacity of 90 m (300 feet), and flow rates are
adjustable from less than 100 mL/rnin to over 5 L/min, depending on pump lift.
The QED Model 400 controller is a microprocessor-based controller and was used to control the flow of
compressed nitrogen, obtained from a cylinder at the wellhead, to the bladder pump. The controller has a
weatherproof keypad and a liquid crystal display and is packaged in a durable case that can be hand carried.
The controller has overall dimensions of!8x!4x7.5 inches and a weight of 17 pounds. Drive gas for the
bladder pump can be delivered from compressed gas cylinders or from a field-portable gasoline- or electric-
powered compressor.
Costs for the two bladder pumps tested range from $525 to $650 each and the controller is priced at $2,595.
Teflon-lined polyethylene tubing is also a requirement for most VOC sampling applications and is priced at
$3.30 per foot.
The Model T1220M and T1250 differ only in size. The pumps were used interchangeably in the study and
their performance results are combined. Hereafter, the two pump models are simply referred to as the Well
Wizard sampler.
VERIFICATION OF PERFORMANCE
The following performance characteristics of the Well Wizard dedicated sampling system were
observed:
Precision: The precision of the sampler was determined through the collection of a series of replicate
samples from 4 standpipe trials using low (-20 |Jg/L) and high (-200 |Jg/L) VOC concentrations at 17-
foot and 91-foot collection depths. Each trial included 6 target VOCs for a total of 24 cases. Well
Wizard sampler precision, represented by the relative standard deviation, for all compounds at all
concentrations and sampling depths evaluated in this study, ranged from 3.9 to 19.7%, with a median
value of 7.7%. In 14 cases the relative standard deviation of the Well Wizard samples was greater than
the reference, with Well Wizard precision less than or equal to reference sample precision in the other 10
cases. The F-ratio test was used to assess whether the observed precision differences were statistically
significant. Test results showed that precision differences between Well Wizard and reference samples
were statistically insignificant at the 95% confidence level in 22 of the 24 cases.
Comparability with a Reference: Well Wizard results from the standpipe trials were compared with
results obtained from reference samples collected at the same time. Both Well Wizard and reference
samples were analyzed by the same analytical method using the same GC/MS system. Sampler
comparability is expressed as percent difference relative to the reference data. Sampler differences for
all target VOCs at all concentrations and sampler depths in this study ranged from -17 to 20%, with a
median difference of 1%. The t-test for two sample means was used to assess whether the differences
between Well Wizard and reference sample results were statistically significant. These tests showed that
in 22 of 24 trials, differences were statistically indistinguishable from 0% at the 95% confidence level.
Statistically significant Well Wizard negative bias did not exceed 17%.
EPA-VS-SCM-41 The accompanying notice is an integral part of this verification statement. August 2000
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Versatility: Sampler versatility is the consistency with which the sampler performed over the range of
target compound volatility, concentration level, and sampling depth. Well Wizard performance did not
vary with changes in compound, concentration, or sampler depth. Thus, the Well Wizard is regarded as
a widely versatile sampling device and applicable for sampling the types of VOCs likely to be
encountered under actual field conditions.
Logistical Requirements: The sampler can be deployed and operated in the field by one person. A half-
day of training is generally adequate to become proficient in the use of the system. The system requires
a source of compressed air or nitrogen at the wellhead, such as a compressed gas cylinder or a gas- or
electric-powered compressor. The bladder pumps are designed for dedicated use in a single monitoring
well and are not intended for portable use.
Overall Evaluation: The results of this verification test show that the Well Wizard bladder pump and
associated pneumatic controller can be used to collect VOC-contaminated water samples that are
statistically comparable to reference samples when analyzed with a common analytical method. The
system is designed for use in well-sampling programs that incorporate low-volume purge methodologies.
As with any technology selection, the user must determine if this technology is appropriate for the
application and the project data quality objectives. For more information on this and other verified
technologies, visit the ETV web site at http://www.epa.gov/etv.
Gary J. Foley, Ph.D.
Director
National Exposure Research Laboratory
Office of Research and Development
Samuel G. Varnado
Director
Energy and Critical Infrastructure Center
Sandia National Laboratories
NOTICE: EPA verifications are based on evaluations of technology performance under specific, predetermined
criteria and appropriate quality assurance procedures. The EPA and SNL make no expressed or implied
warranties as to the performance of the technology and do not certify that a technology will always operate as
verified. The end user is solely responsible for complying with any and all applicable federal, state, and local
requirements. Mention of commercial product names does not imply endorsement.
EPA-VS-SCM-41 The accompanying notice is an integral part of this verification statement.
August 2000
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EPA/600/R-00/062
August 2000
Environmental Technology
Verification Report
Groundwater Sampling Technologies
QED Environmental Systems Inc.
Well Wizard® Dedicated Sampling
System
by
Wayne Einfeld
Sandia National Laboratories
Albuquerque, New Mexico 87185
and
Eric N. Koglin
U.S. Environmental Protection Agency
Environmental Sciences Division
National Exposure Research Laboratory
Las Vegas, Nevada 89193-3478
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Notice
The U.S. Environmental Protection Agency (EPA), through its Office of Research and Development (ORD),
funded and managed, through Interagency Agreement No. DW66940927 with Sandia National Laboratories,
the verification effort described herein. This report has undergone peer and administrative review and has
been approved for publication as an EPA document. Mention of trade names or commercial products does not
constitute endorsement or recommendation for use of a specific product.
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Table of Contents
List of Figures iv
List of Tables iv
Acknowledgments v
Abbreviations and Acronyms vi
1 INTRODUCTION 1
Background 1
Demonstration Overview 1
2 TECHNOLOGY DESCRIPTION: QED ENVIRONMENTAL WELL WIZARD DEDICATED SAMPLING
SYSTEM 3
3 DEMONSTRATION PROCESS AND DESIGN 5
Introduction 5
Site Description 5
Verification Test Design Summary 7
Test Design Elements 7
Sampler Performance Parameters 8
Sample Analysis 10
Data Processing 10
Data Quality Control 10
Verification Test Plan 11
Standpipe and Groundwater Well-Sampling Matrix 11
Chronological Summary of Demonstration Activities 12
Deviations from the Verification Plan 13
4 PERFORMANCE EVALUATION FOR WELL WIZARD DEDICATED SAMPLING SYSTEM 15
Introduction 15
Sampler Precision 15
Sampler Comparability 16
Blank and Clean-Through-Dirty Test Results 18
Monitoring Well Results 18
Sampler Versatility 18
Deployment Logistics 18
Performance Summary 19
5 WELL WIZARD TECHNOLOGY UPDATE AND REPRESENTATIVE APPLICATIONS 21
Well Wizard Sampling System Types and Configurations 21
System Components 21
New Product Development 21
Typical Applications 21
Users' References 22
6 REFERENCES 23
APPENDICES
A: REFERENCE PUMP PERFORMANCE 25
B: QUALITY SUMMARY FOR ANALYTICAL METHOD 29
ill
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List of Figures
1 The standpipe attheUSGS Hydrological Instrumentation Facility 6
2 Well Wizard comparability with reference samples from the standpipe trials 16
A-1 Percent recoveries of the reference pump by compound for the four standpipe trials 28
B-l Calibration check control chart for TCE on GC/MS #1 30
B-2 Calibration check control chart for TCE on GC/MS #2 31
B-3 Calibration check control chart for PCE on GC/MS #1 31
B-4 Calibration check control chart for PCE on GC/MS #2 32
B-5 GC/MS system check relative percent differences 32
List of Tables
1 Construction Details of Groundwater Monitoring Wells 7
2 Target VOCs 7
3 Sampler Verification Trials at the Standpipe 12
4 Sampler Verification Trials at the Groundwater Monitoring Wells 12
5 Precision Summary for Well Wizard and Reference Sampler 15
6 Comparability of Well Wizard and Reference S ample Data from Standpipe Trials 17
7 Well Wizard and Reference Sampler Results from Groundwater Monitoring Wells 19
8 Performance Summary for Well Wizard Dedicated Sampling System 20
A-l Precision of Gear Pump and Reference Samples in Standpipe Trials 26
A-2 Comparability of the Gear Pump with the Reference Samples in Standpipe Trials 27
B-l Onsite GC/MS-Headspace Method Quality Control Measures 29
IV
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Acknowledgments
The authors acknowledge the support of all those who helped in the vendor solicitation, planning, field
deployment, and analysis phases of this verification test. In particular, we recognize Steve Gardner (US EPA
NERL, Las Vegas), who provided technical assistance and peer reviewed the test plan. We also acknowledge
the assistance of Eugene Hays, Bill Davies, and Ed Ford (US Geological Survey) in providing access to the
Standpipe Facility at the NASA Stennis Space Center, as well as for their administrative and logistical
support during the standpipe and groundwater monitoring trials. We also thank Ronald McGee and Jenette
Gordon (NASA, Environmental Management) for their willingness to grant us access to the groundwater
monitoring wells at the NASA Stennis Space Center. Thanks also to Greg New (Foster Wheeler
Environmental Corporation) for his assistance in getting much of the site hydrological and well monitoring
data into our hands during the planning phases of this test. Finally, we thank Craig Crume and Mika
Geenfield (Field Portable Analytical) for their long hours, care, and diligence in onsite sample analysis during
the field trials.
For more information on the Groundwater Sampling Technology Verification Test, contact
Eric Koglin Wayne Einfeld
Pilot Manager ETV Project Manager
Environmental Protection Agency Sandia National Laboratories
Environmental Sciences Division MS-0755 P.O. Box 5800
National Exposure Research Laboratory Albuquerque, NM 87185-0755
P.O. Box 93478 (505) 845-8314 (v)
Las Vegas, NV 89193-3478 E-mail: weinfel@sandiagov
(702) 798-2432 (v)
E-mail: koglin.eric@epa.gov
For more information on the QED Environmental Well Wizard dedicated sampling system, contact
David Kaminski
QED Environmental Systems Inc.
P.O. Box 30873
Walnut Creek, CA 94598
800-366-7610 (v)
E-mail: davidkqed@aol.com
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Abbreviations and Acronyms
BNZ
DIFF
EPA
ETV
GC/MS
fflF
MSL
MW
NASA
ND
NERL
PCE
PTFE
PVC
QA
QC
KEF
RPD
RSD
SCMT
SNL
SP
SSC
TCE
USGS
VOC
12DCA
11DCE
112TCA
Benzene
Difference
US Environmental Protection Agency
Environmental Technology Verification Program
Gas chromatograph-mass spectrometer
Hydrological Instrumentation Facility
Mean sea level
Monitoring well
National Aeronautics and Space Administration
Not detected
National Exposure Research Laboratory
Tetrachloroethene (perchloroethene)
Polytetrafluoroethylene
Polyvinyl chloride
Quality assurance
Quality control
Reference
Relative percent difference
Relative standard deviation
Site Characterization and Monitoring Technologies Pilot
Sandia National Laboratories
Sample port
Stennis Space Center
Trichloroethene
US Geological Survey
Volatile organic compound
1,2-dichloroethane
1,1 -dichloroethene
1,1,2-trichloroethane
VI
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Section 1 — Introduction
Background
The U.S. Environmental Protection Agency (EPA)
has created the Environmental Technology
Verification Program (ETV) to facilitate the
deployment of innovative or improved
environmental technologies through performance
verification and dissemination of information. The
goal of the ETV Program is to further
environmental protection by substantially
accelerating the acceptance and use of improved
and cost-effective technologies. ETV seeks to
achieve this goal by providing high-quality, peer-
reviewed data on technology performance to those
involved in the design, distribution, financing,
permitting, purchase, and use of environmental
technologies.
ETV works in partnership with recognized
standards and testing organizations and
stakeholder groups consisting of regulators,
buyers, and vendor organizations, with the full
participation of individual technology developers.
The program evaluates the performance of
innovative technologies by developing test plans
that are responsive to the needs of stakeholders,
conducting field or laboratory tests (as
appropriate), collecting and analyzing data, and
preparing peer-reviewed reports. All evaluations
are conducted in accordance with rigorous quality
assurance (QA) protocols to ensure that data of
known and adequate quality are generated and that
the results are defensible.
ETV is a voluntary program that seeks to provide
objective performance information to all of the
participants in the environmental marketplace and
to assist them in making informed technology
decisions. ETV does not rank technologies or
compare their performance, label or list
technologies as acceptable or unacceptable, seek
to determine "best available technology," or
approve or disapprove technologies. The program
does not evaluate technologies at the bench or
pilot scale and does not conduct or support
research.
The program now operates 12 pilots covering a
broad range of environmental technology areas.
ETV has begun with a 5-year pilot phase (1995-
2000) to test a wide range of partner and
procedural alternatives in various pilot areas, as
well as the true market demand for and response to
such a program. In these pilots, EPA utilizes the
expertise of partner "verification organizations" to
design efficient processes for conducting
performance tests of innovative technologies.
These expert partners are both public and private
organizations, including federal laboratories,
states, industry consortia, and private sector
facilities. Verification organizations oversee and
report verification activities based on testing and
QA protocols developed with input from all major
stakeholder/customer groups associated with the
technology area. The demonstration described in
this report was administered by the Site
Characterization and Monitoring Technologies
(SCMT) Pilot. (To learn more about ETV, visit
ETV's Web site at http://www.epa.gov/etv.)
The SCMT pilot is administered by EPA's
National Exposure Research Laboratory (NERL).
Sandia National Laboratories (SNL), one of two
verification organizations associated with the
SCMT pilot, conducted a verification study of
groundwater sampling technologies during the
summer of 1999. Groundwater sampling
technologies are commonly employed at
environmental sites for site screening and
characterization, remediation assessment, and
routine environmental monitoring. Groundwater
sampling technologies generally fall into two
categories: (1) active systems, including pumping
systems and discrete-level grab systems; and (2)
passive or diffusional systems. Both types of
samplers were evaluated during this verification
study.
Demonstration Overview
In August 1999, a demonstration study was
conducted to verify the performance of six
groundwater sampling devices: Multiprobe 100
(Burge Environmental, Tempe, AZ), SamplEase
(Clean Environment Equipment, Oakland, CA),
Micro-Flo (Geolog Inc., Medina, NY), Kabis
Sampler (Sibak Industries, Solano Beach, CA),
GoreSorber (W. L. Gore and Associates, Elkton,
MD), and the Well Wizard dedicated sampling
system (QED Environmental, Ann Arbor, MI).
This report contains an evaluation of the Well
Wizard dedicated sampling system.
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It is important to point out that the scope of this
technology demonstration was purposely limited
to sampling device performance parameters, such
as precision, comparability with a reference
measurement, and where applicable, deployment
logistics. Several of the systems tested in this
study are intended for use with low-flow sampling
protocols—a relatively new approach to the
collection of a representative sample from a
groundwater monitoring well. This study was
specifically intended to evaluate sampling device
performance and did not evaluate the merits of a
low-flow purge and sampling protocol. This
protocol has been proposed, tested, and published
elsewhere [Puls and Barcelona, 1996] and is
beyond the scope of this particular investigation.
The demonstration was conducted in August of
1999 at the National Aeronautics and Space
Administration (NASA) Stennis Space Center
(SSC) in southwestern Mississippi. Sandia
worked in cooperation with the US Geological
Survey (USGS), a federal agency resident at the
NASA Stennis site, and used a 100-foot standpipe
testing facility associated with the USGS
Hydrological Instrumentation Facility (HIF)
located on the NASA site. The standpipe, serving
as an "aboveground" well, was filled with water
spiked with various concentration levels of six
target volatile organic compounds (VOCs). Water
sampling ports along the exterior of the pipe
permitted the collection of reference samples at
the same time that groundwater sampling
technologies collected samples from the interior of
the pipe.
The standpipe trials were supplemented with
additional trials at a number of groundwater
monitoring wells at sites with VOC-contaminated
groundwater at the NASA Stennis facility. The
devices were deployed in a number of 2-inch and
4-inch wells, along with reference samplers for
comparison. The principal contaminant at the site
was trichloroethene.
All technology and reference samples were
analyzed by the same field-portable gas
chromatograph-mass spectrometer (GC/MS)
system that was located at the test site during the
verification tests. The overall performance of the
groundwater sampling technologies was assessed
by comparing technology and reference sample
results for a number of volatile organic
compounds, with particular attention given to key
parameters such as sampler precision and
comparability with reference sample results.
Aspects of field deployment and potential
applications of the technology were also
considered.
A brief outline of this report is as follows: Section
2 contains a brief description of the Well Wizard
bladder pump and its capabilities. Section 3
outlines a short description of the test facilities and
a summary of the verification test design. Section
4 includes a technical review of the data, with an
emphasis on assessing overall sampler
performance. Section 5 presents a summary of the
Well Wizard dedicated sampling system and
provides examples of potential applications of the
sampler in site characterization and monitoring
settings. Appendix A contains performance data
for the reference pump and Appendix B presents
an assessment of quality control data associated
with the analytical method used in this study.
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Section 2 — Technology Description: QED Environmental
Well Wizard Dedicated Sampling System
This section provides a general description and
overview of the capabilities of the QED
Environmental Well Wizard bladder pump. QED
Environmental provided the information used to
prepare this section.
The Well Wizard bladder pump consists of an
internal flexible bladder that is positioned within a
rigid pump body such as polyvinyl chloride, Teflon,
or stainless steel. The inner bladder is equipped
with one-way inlet and outlet valves and passively
fills with water when the pump is at depth by virtue
of hydrostatic pressure. Following the fill cycle,
compressed air or nitrogen from a cylinder or
compressor at the wellhead is driven down to the
pump through tubing and is used to compress the
bladder, thus driving the water sample up to the
surface through a second tubing line. The pumping
sequence consists of repeated fill-compress cycles,
using a pneumatic controller positioned at the
wellhead. With the controller, the duration and
frequency of the fill-compress cycles can be varied
to deliver the desired flow rate at the wellhead. The
bladder design offers the advantage of minimizing
sample turbulence, which can result in loss of
VOCs in the sample, as well as eliminating contact
of the water sample with the compressed air or
nitrogen used to lift the sample to the surface.
QED Environmental offers a line of bladder pumps
manufactured with various materials. Two pumps
tested during this evaluation were the Model
T1220M and the T1250. These pumps were
essentially the same in design and construction
materials with the exception of length—the Model
1220 was 1.04 m in length and the 1250 was 0.38 m
in length. Both pumps use polytetrafluoroethylene
(PTFE) Teflon for the bladder material and 316
stainless steel for the pump body, fittings, and
intake screen. The external diameter of both pumps
was 3.8 cm (1.5 inches). The pump intake stainless
steel screen mesh was 0.25 mm (0.01 inch). Both
pumps have a maximum lift capacity of 90 m (300
feet), and flow rates are adjustable from less than
100 mL/min to over 5 L/min, depending on pump
lift.
The QED Model 400 controller is a
microprocessor-based controller and was used to
control the flow of compressed nitrogen, obtained
from a cylinder at the wellhead, to the bladder
pump. The controller has a weatherproof keypad
and a liquid crystal display and is packaged in a
durable case that can be hand carried. The
controller has overall dimensions of 18 x 14 x 7.5
inches and a weight of 17 pounds. Drive air for the
bladder pump can be delivered from compressed
gas cylinders or from a field-portable gasoline or
electric-powered compressor.
Costs for the two bladder pumps tested range from
$525 to $650 each, and the controller is priced at
$2,595. Teflon-lined polyethylene tubing is also a
requirement for most VOC sampling applications
and is priced at $3.10 to $3.40 per foot.
During verification testing at the groundwater
monitoring wells, another QED low-flow purge
accessory was used. A flow cell (Model FC-5000)
for continuous monitoring, display, and recording
of water quality parameters was a component of the
sampling system. The use of this accessory was for
demonstration purposes only, and a performance
assessment of the flow cell was not a part of the
formal verification test.
The QED bladder pump systems are designed for
dedicated well-sampling applications. The bladder
pump and tubing are left in the well and the
controller unit and drive gas source are moved from
well to well during typical sampling operations.
Additional information on potential applications of
the system for environmental characterization and
monitoring can be found in Section 5.
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Section 3 — Demonstration Process and Design
Introduction
The principal objective of this demonstration was
to conduct an independent evaluation of the
capabilities of several ground-water sampling
technologies for VOC-contaminated water. A
number of key performance parameters were
chosen to evaluate overall sampler performance.
In order to ensure data integrity and authenticity of
results, data quality control measures were also
incorporated into the study design. The design
was developed by personnel at Sandia National
Laboratories with concurrence from the various
technology vendors participating in the study.
Technical review of the study design was also
provided by EPA personnel with professional
expertise in the area of groundwater sampling. A
complete demonstration plan has been published
[Sandia, 1999].
Site Description
The John C. Stennis Space Center in southwest
Mississippi is one often NASA field centers in the
United States. It is NASA's primary center for
testing and flight-certifying rocket propulsion
systems for the Space Shuttle and future generations
of space vehicles. Over the years, SSC has evolved
into a multiagency, multidisciplinary center for
federal, state, academic and private organizations
engaged in space, oceans, environmental programs,
and national defense. The Hydrological
Instrumental facility supports USGS agency-wide
hydrologic data-collection activities through the
identification of agency needs, development of
technical specifications, and testing and
evaluation.
Standpipe Facility—One of the HIF test centers is
known as the Standpipe Facility. The facility was
designed by Doreen Tai, an HIF chemical
engineer, and is housed in a Saturn V rocket
storage building at the Stennis complex. A
schematic diagram of the Standpipe and
accessories is shown in Figure 1. The Standpipe is
an aboveground, 100-foot-long, 5-inch-diameter,
stainless steel pipe with numerous external
sampling ports along its length. Two large tanks
at the top of the Standpipe are used to prepare
solutions that can then be drained into the
Standpipe. The tanks are equipped with motor-
driven mixing propellers and floating lids to
minimize loss of volatile compounds during
mixing and transfer of solution. An external
Standpipe fill line at the bottom of the pipe enables
the pipe to be filled from the bottom up, thereby
minimizing flow turbulence and VOC losses in the
prepared solutions. The external access ports
allow reference samples to be taken
simultaneously with technology samples inside the
pipe. As shown in Figure 1, the indoor facility has
six levels of access, including the ground floor,
and all levels are serviced by a freight elevator. In
this demonstration, the Standpipe was used in a
series of controlled water sampling trials.
Technology vendors sampled VOC-contaminated
water solutions from the Standpipe while reference
samples were simultaneously taken from the
external ports.
Site Hydrogeology—The second phase of this
technology demonstration involved the collection
of groundwater samples from six onsite wells at
SSC. The site has about 200 wells that have been
used for subsurface plume characterization and
routine groundwater monitoring. The shallow,
near-surface geology where most of the
contaminant plumes are located can be
summarized as follows [Foster Wheeler, 1998]:
The geology generally consists of a thin veneer of
clayey sediments known as Upper Clay, found at
elevations ranging from 10 to 30 feet above mean
sea level (MSL). These overlay a sandy unit
named the Upper Sand (at 5 to 15 feet above
MSL). The Upper Sand is underlain by a second
clayey unit named the Lower Clay and a second
sandy unit called the Lower Sand (at -35 to 5 feet
MSL). Below the Lower Sand, another clayey
unit is present which represents an unnamed or
undifferentiated Pleistocene deposit. This deposit
is underlain by a thick zone of inter-bedded sand
and clay deposits that form the Citronelle
Formation (at -100 to -40 feet MSL). The VOC
contamination is present in the Upper Sand and
Lower Sand water-bearing zones;
correspondingly, most of the wells selected for use
in this test were screened in these zones.
Groundwater Monitoring Wells—Construction
information for the six wells selected for use in
this study is given in Table 1. The wells were
constructed with either 2- or 4-inch-diameter
polyvinylchloride (PVC) pipe with a 10-foot PVC
screen length. All samples were collected at the
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5 IN. DIA.-
SP14 fi
5P13
SP12
SPii
SP10
SP9
SPS
SP?
SPS
5P3
SP2
SPt
HOLDINS TftNKS
FLOAT IN8 IOP
LEVEL 5
-I IN. DIA. FIIL/DRA1M LlhE
LEVEL 4
LEVEL 3
5P - SAMPLINS PORT
SP DISTANCE FROM TO1 MATER LEVEL
SPI3 17.5 ft.
SPS 54 ft.
3P7 m ft.
SP4 82 ft,
SP2 92 Ft,
LEVEL 2
/EXIT LINE
Figure 1. The stand pipe at the USGS Hydrological Instrumentation Facility.
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mid-screen level. Typical sampling depths for the
wells selected for study ranged from about 15 to
85 feet from the top of the well column to the
screen midpoint. The depth of the water column
above the midscreen point ranged from 5 to 68
feet for the wells selected for use in this study.
Verification Test Design Summary
The verification test design consisted of two basic
elements. The first was a test matrix consisting of
several trials conducted under carefully controlled
sampling conditions at the standpipe. These trials
enabled sampler performance parameters, such as
precision and comparability with reference, to be
evaluated. The second element was an additional
series of tests conducted under actual field
conditions with inherently less experimental
control. These trials presented an opportunity to
observe the technology in actual field use in
conditions very similar to those that would be
encountered in routine use. Together, these two
study elements provided a data set that is adequate
for an overall performance assessment of these
groundwater sampling devices for applications
specifically involving the sampling of VOC-
contaminated groundwater.
Test Design Elements
The test consisted of a variety of sampling
activities carried out under relatively closely
controlled experimental conditions at the
standpipe, along with field sampling at selected
onsite monitoring wells under less controlled
conditions. Additional design element
descriptions are given below. The participating
technologies were split into two categories, active
samplers and passive samplers, with individual
sampling trials designed specifically for these two
categories.
Target VOCs—Six target compounds, all
regulated under the EPA Clean Water Act, were
selected for testing in this study. The compounds
were 1,2-dichloroethane (12DCA), 1,1-
dichloroethene (11DCE), trichloroethene (TCE),
benzene (BNZ), tetrachloroethene (PCE), and
1,1,2-trichloroethane (112TCA). With the
exception of benzene, all of these compounds are
chlorinated and have regulatory limits of 5 |jg/L in
water as presented in the Clean Water Act. The
six compounds selected encompass a range of
volatility, a parameter that is likely to influence
sampler performance. Target compound volatility,
as represented by Henry's constants and boiling
point information, is given in Table 2.
Table 1. Construction Details of Groundwater Monitoring Wells
Well
No.
06-04
06-10
06-11
06-20
12-09
12-12
TOC
(ft, MSL)
28.8
7.8
15.3
7.3
28.0
28.4
Total
Depth
(ft)
39.0
87.0
150.0
75.0
18.0
99.0
Screen Elev.
(ft, MSL)
Top
-1.3
-55.2
J62.8
-55.4
18.0
-11.0
Bottom
-11.3
-65.2
-72.8
-65.4
8.0
^21.0
Well
Diam.
(in)
2
4
4
4
2
4
Install
Date
04/95
04/95
05/95
12/96
05/95
05/95
Depth
to
Water
(ft)
24.6
8.2
15.2
7.8
10.0
11.6
Water
Level
(ft,
MSL)
4.2
4D.4
0.1
-0.6
18.0
16.8
Water Depth
Above
Screen
Midpoint
(ft)
10.5
59.8
67.9
59.8
5.0
32.8
Notes: TOC = top of well column; water levels from most recent quarterly well-monitoring data.
Table!. Target VOCs
Compound
Tetrachloroethene (PCE)
1,1-Dichloroethene(11DCE)
Trichloroethene (TCE)
Benzene (BNZ)
1 ,2-Dichloroethane (12DCA)
1 ,1 ,2-Trichloroethane (1 12TCA)
Henry's Constant
(kg* bar/mole at 298 K)a
High (17.2)
High (29.4)
Mid (10.0)
Mid (6.25)
Low (1 .39)
Low (0.91)
Boiling Pt.
(°C)
121
32
87
80
84
114
Henry's constant data from NIST, 2000.
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Test Concentrations—The use of the standpipe
facility enabled the preparation of water mixtures
containing the six target VOCs in a range of
concentration levels. In four standpipe testing
trials, the target compound concentration was
either low (10-20 |ag/L) or high (175-225 |ag/L).
Spike solutions of all six target compounds were
prepared in methanol from neat compounds.
Normally a 5-10-mL volume of the spiking
solution was injected into the mixing tank, which
was located at the top of the standpipe and
contained about 100 gallons of tap water. This
solution was covered with a floating lid to reduce
volatile losses, gently mixed for 5 minutes, and
then drained into the standpipe.
Standpipe Reference Samples—Preliminary
studies at the standpipe revealed volatile losses of
target compounds during mixing and filling.
Consequently, calculated spike concentrations
could not be used as reference values in this study.
The standpipe has external sampling ports along
its length so that reference samples could be
collected simultaneously with the samples from
the interior of the pipe with devices undergoing
testing. Each sampling trial consisted of the
simultaneous collection of replicate test device and
reference samples at a fixed concentration and
sampling depth. The reference samples were
collected directly into analysis vials with no
intervening pumps or filters that could affect the
sample. The use of multiple sequentially collected
samples allowed the determination of test device
and reference sampler precision. Precision in this
context incorporates the variability of the
technology and the reference sampler in
combination with the common analytical method
used on both sample types. The reference sampler
precision is assumed to be the baseline with which
the technology precision data can be directly
compared for each of the sampling trials.
Sampler Blank—The standpipe trials included a
blank test in which replicate samples were
collected from a blank water mixture in the
standpipe. This test was conducted to assess
whether the construction materials in the various
samplers could be a source of contamination of the
sample for the six target compounds used in this
study.
Sampler Carryover—One of the intended
applications of several of the samplers involved in
the study is the collection of a water sample with
relatively low VOC levels at a discrete level in a
well that may have overlying layers of VOC
contamination at higher levels. A so-called clean-
through-dirty test was incorporated to assess the
degree to which the samplers were contaminated
in the high-level layer that was penetrated as the
sampler was lowered to a cleaner underlying layer
in the well. The results of these trials are also
expressed in terms of percent difference from
reference samples, with recovery values
significantly greater than zero indicating sampler
contamination from the overlying contaminated
layers in the well.
Groundwater Well Reference Samples—Six onsite
groundwater monitoring wells were selected for
the second phase of the study. A submersible
electric gear pump (Fultz, Model SP-300) was
chosen as a reference sampling device for these
additional field tests. Verification studies on the
performance of this pump were carried out during
the standpipe phase of the experiments to provide
technical data substantiating its use as a reference
technology in the field. A more complete
description of the sampling device, along with a
summary of these data, is given in Appendix A.
During field sampling events, the reference pump
was colocated in the well with the sampling
devices in order to obtain simultaneous reference
samples from the well. Teflon tubing ('/t-inch
outside diameter) was used to transport the water
sample from the reference pump outlet to the
collection vial at the wellhead. During all
sampling, the reference pump was operated at a
low flow rate (100-200 mL/min).
As noted previously, the field sampling trials were
not an evaluation of the low-flow purge
methodology for well sampling. Consequently,
water quality parameters were not monitored in
the field sampling trials. A purge was used to
flush the reference pump and tubing to ensure that
the pump was drawing from the well column
water. Whether formation water was being
sampled was of secondary importance in this
sampling plan.
Sampler Performance Parameters
Four performance parameters were evaluated in
the assessment of each technology. They are
briefly outlined in the following paragraphs.
Precision—Sampler precision was computed for
the range of sampling conditions included in the
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test matrix by the incorporation of replicate
samples from both the standpipe and the
groundwater monitoring wells in the study design.
The relative standard deviation (RSD) was used
as the parameter to estimate precision. The percent
relative standard deviation is defined as the sample
standard deviation divided by the sample mean
times 100, as shown below:
%DIFF =
• 100
X
• 100
Here, Xt is one observation in a set of n replicate
samples where X is the average of all
observations, and n is the number of observations
in the replicate set. In our assessment of sampler
precision, we used a statistical test to assess
whether differences between the reference sample
precision and the technology sample precision
were statistically significant. Specifically, the F-
ratio test compares the variance (square of the
standard deviation) of the two groups to provide a
quantitative assessment as to whether the observed
differences between the two variances are the
result of random variability or the result of a
significant influential factor in either the reference
or technology sample groups [Havlicek and Grain
1988a].
Comparability—The inclusion of reference
samples, collected simultaneously with technology
samples from the external sampling port of the
standpipe, allows the computation of a
comparability-to-reference parameter. The term
comparability is to be distinguished from the term
accuracy. Earlier investigations at the standpipe
revealed that volatility losses occurred when the
spike mixtures were mixed and transported during
standpipe filling. As a result, the "true"
concentrations of target VOCs in the standpipe
were not precisely known and thus an accuracy
determination is not warranted Alternatively, a
reference measurement from the external port,
with its own sources of random error, is used for
comparison. The term percent difference is used
to represent sampler comparability for each of the
target compounds in the sampling trials at the
standpipe. Percent difference is defined as
follows:
where is XM, the average reported concentration
of all technology sample replicates and X ™t is the
average reported concentration of all reference
sample replicates. The t-test for two sample
means was used to assess differences between the
reference and technology means for each sampling
trial [Havlicek and Grain, 1988b]. The t-test gives
the confidence level associated with the
assumption that the observed differences are the
result of random effects among a single population
only and that there is no significant bias between
the technology and reference methods.
Versatility—The versatility of the sampler was
evaluated by summarizing its performance over
the volatility and concentration range of the target
compounds, as well as the range of sampling
depths encountered in both the standpipe and the
groundwater monitoring well trials. A sampler
that is judged to be versatile operates with
acceptable precision and comparability with
reference samples over the range of experimental
conditions included in this study. Those samplers
judged to have low versatility may not perform
with acceptable precision or comparability for
some of the compounds or at some of the tested
sampling depths.
Field Deployment Logistics—This category refers
to the logistical requirements for deployment of
the sampler under its intended scope of
application. This is a more subjective category
that incorporates field observations made during
sampler deployment at the groundwater
monitoring wells. Logistical considerations
include such items as personnel qualifications and
training, ancillary equipment requirements, and
field portability.
Operator Influence—The sampling technician as
well as the sample collection method have an
influence on the overall quality of the samples
taken. This is particularly true for the active
samplers evaluated in this study. Such factors as
the sample flow rate when filling the vial with a
bladder pump, the cycle times and volume of
bladder pump and others may influence overall
sample quality. An evaluation of operator
influence on sample quality is beyond the scope of
-------
this study. All operators were experienced in the
use of their technologies and the assumption is
made that these operators were operating their
sampling devices under conditions that would
yield the highest quality samples.
Sample Analysis
A single analytical method was used for
technology and reference samples. All analyses
were conducted onsite, using analytical services
provided by Field Portable Analytical (Fremont,
CA). The onsite instrumentation consisted of two
identical field-portable gas chromatograph-mass
spectrometer units (Inficon, HAPSITE, Syracuse,
NY) equipped with an Inficon headspace sampling
system. The analysis method used was a modified
Method 8260 (purge-and-trap GC/MS) with
headspace sampling replacing the purge-and-trap
portion of the method [EPA, 1996]. Throughput
was on the order of 4 to 6 samples per hour per
instrument for a daily throughput of 60-70
samples per instrument. The Inficon field-portable
GC/MS system with headspace vapor sampling
accessory had previously gone through the ETV
verification process. Results from this verification
study showed that system accuracy and precision
for VOCs in water analysis were comparable with
a conventional fixed laboratory analysis using
purge-and-trap sample handling combined with
bench-top GC/MS analytical systems [EPA,
1998].
A brief summary of the analytical method follows:
Samples were brought to the analysis location in
40-mL volatile organic analysis (VOA) vials and
kept at temperatures near 4 °C until they were
prepared for instrument analysis. As a result of
the relatively high sample throughput and the use
of two instruments, sample holding times did not
exceed 24 hours in most cases. Consequently, no
sample preservatives were used in the study.
Immediately prior to analysis, the chilled VOA
sample vials were uncapped and immediately
transferred to a 50-mL glass syringe. Half (20
mL) of the sample was then transferred to a
second 40-mL VOA vial and the vial was
immediately capped. A 5-|jL solution containing
internal standards and surrogate standards was
injected through the septum cap of the vial. The
vial was then placed in the headspace sampling
accessory and held at 60 °C for 15 minutes. The
original vial was again filled with the remainder of
the sample, capped, and held under refrigeration as
a spare. Following the temperature equilibration
time, a vapor extraction needle was inserted
through the vial's septa cap and into the
headspace. A pump in the GC/MS then sampled a
fixed volume of headspace gas through a heated
gas transfer line and in a fixed-volume gas
sampling loop in the GC/MS. Under instrument
control, the gas sample was then injected onto the
capillary column for separation and subsequent
detection. An integrated data system processed
the mass detector data and output results for the
six target analytes, plus internal and surrogate
standards, in concentration format. The method
used the internal standard method (as outlined in
Method 8260) for computation of target compound
concentrations. Surrogate standard results were
used as measures of instrument data quality, along
with other quality control measures outlined
below.
Data Processing
The results from chemical analysis of both
technology and reference samples were compiled
into spreadsheets and the arithmetic mean and
percent relative standard deviation (as defined in
Section 3) were computed for each set of replicate
samples from each standpipe and monitoring well
trial. All data were reported in units of
micrograms per liter for the six target compounds
selected. Direct trial-by-trial comparisons were
then made between technology and reference
sample results as outlined below. All the
processed data from the verification study have
been compiled into data notebooks and are
available from the authors by request.
Data Quality Control
The desirability of credible data in ETV
verification tests requires that a number of data
quality measures be incorporated into the study
design. Additional details on data quality control
are provided in the following paragraphs.
Sample Management—All sampling activities
were documented by SNL field technicians using
chain-of-custody forms. To save sample handling
time and minimize sample labeling errors in the
field, redundant portions of the chain-of-custody
forms and all sampling labels were printed prior to
the field demonstration.
Field Logbooks—Field notes were taken by
observers during the standpipe and groundwater
well-sampling trials. The notes include a written
chronology of sampling events, as well as written
10
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observations of the performance characteristics of
the various technologies tested during the
demonstration.
Predemonstration Analytical System Audit—Prior
to the actual demonstration, a number of samples
containing the six target compounds at various
concentration levels were prepared at Sandia
National Laboratories and sent via overnight mail
in an icepack to Field Portable Analytical near
Sacramento, CA. They were analyzed by GC/MS
using the headspace method intended for use in the
final field test. Results from this preliminary audit
revealed acceptable performance of the GC/MS
system and its accompanying method. The written
analytical method that was used during the full
demonstration was also reviewed and finalized at
this time.
Analytical Method—The analytical method was an
adaptation of EPA Method 8260B and followed
the data quality requirements outlined in the
method. Included in the list of data quality
measures were (1) initial calibration criteria in
terms of instrument linearity and compound
recovery, (2) daily instrument calibration checks at
the onset and completion of each 12-hour analysis
shift, (3) blank sample instrument performance
checks, (4) internal standard recovery criteria, and
(5) surrogate standard recovery criteria. A
summary of the GC/MS analysis quality control
data for the demonstration period is given in
Appendix B.
Verification Test Plan
The preceding information, as well as that which
follows, is summarized from the Groundwater
Sampling Technologies Verification Test Plan
[Sandia, 1999], which was prepared by SNL and
accepted by all vendor participants prior to the
field demonstration. The test plan includes a more
lengthy description of the site, the role and
responsibilities of the test participants, and a
discussion of the experimental design and data
analysis procedures.
Standpipe and Groundwater Well-
Sampling Matrix
The sampling matrix for the standpipe sampling
phase of the demonstration is given in Table 3.
All standpipe and groundwater well testing was
carried out sequentially, with the various
participants deploying their sampling devices one
at a time in either the standpipe or the groundwater
monitoring wells. A randomized testing order was
used for each trial. The standpipe test phase
included seven trials. Trials 1 and 2 were carried
out at shallow and deep locations with a low-
concentration (10-20 |Jg/L) standpipe mixture.
Trials 3 and 4 were conducted at shallow and deep
locations with a high-concentration (175-225
|jg/L) standpipe mixture. In all trials, reference
samples were collected from external sampling
ports simultaneously with sample collection by the
device under test.
Trial 5 was a blank mixture measurement at the
standpipe to test the cleanliness of each sampler.
For this trial, the standpipe was filled with tap
water and three replicates were collected by the
device under test from the deep location in the
pipe while three reference replicates were
collected simultaneously from the adjacent
exterior sampling port.
Trials 6 and 7 at the standpipe were termed "clean-
through-dirty" tests and were designed to evaluate
the performance of discrete-level samplers. This
test was optional for the other active samplers.
Those sampling systems that were intended for
permanent deployment in a well were not required
to participate in the "clean-through-dirty"
sampling trials, although some vendors chose to
participate voluntarily. In this test, two mixtures,
a high (-200 |jg/L) and a low (-20 |Jg/L), were
prepared in the mixing tanks. The pipe was then
filled so that the high-level mixture occupied the
top 1/3 of the pipe while the low-level mixture
was in the bottom 2/3 of the pipe. Water samples
were collected at the bottom and approximate
midpoint of the pipe after being lowered through
the high-level mixture at the top of the pipe.
Reference samples were simultaneously collected
from the external sampling ports in the same
manner as for the previous standpipe trials.
The onsite groundwater sampling matrix is shown
in Table 4. Two of the wells originally scheduled
for use were dropped from the sampling matrix
because the TCE concentrations were below
instrument detection limits. The groundwater
sampling procedure for the bladder pump and
reference sampler was as follows: Prior to
insertion into the water column, the reference and
bladder pumps were arranged vertically so that the
reference pump was directly below the bladder
pump. The two sampling devices were then
lowered into the well as a pair. The inlet screen of
11
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Table 3. Sampler Verification Trials at the Stand pipe
Trial No.
1
2
3
4
5
6
7
Standpipe
Collection
Port
SP14
SP3
SP14
SP3
SP3
SP3
SP12
Sample
Collection
Depth (ft)
Shallow (17)
Deep (92)
Shallow (17)
Deep (92)
Deep (92)
Deep (92)
Shallow (35)
VOC Concentration
Level
Low (-20 |jg/L)
Low (-20 |jg/L)
High (-200 ug/L)
High (-200 ^g/L)
Blank
Mixed (high over low)
Mixed (high over low)
No. of Replicates
per
Technology
5
5
5
5
3
4
4
Notes: In each trial, an equal number of reference samples were collected
standpipe sampling ports. Sample collection points during trials 6 and 7
lowered through a high VOC concentration region.
simultaneously with the device samples from adjacent external
were from the low VOC concentration region after the sampler was
Table 4. Sampler Verification Trials at the Groundwater Monitoring Wells
Trial
10
11
13
14
Well
06-20MW
06-1 1MW
06-04MW
12-09MW
Distance from
Top of Well to
Screen Mid-
point (ft)
67.7
83.1
35.1
15.0
Depth to Water
(ft)
7.8
15.2
24.6
10.0
Approximate
TCE Cone.
(119/L)
<5
500
500
20
No. of
Replicates per
Technology
4
4
4
4
Notes: Reference samples were collected using a submersible electric sampling pump that was collocated with the bladder pump in 2- and Cl-
inch wells. Well numbers 06-04 and 12-09 were 2-inch diameter wells. All other wells had 4-inch diameters. Approximate TCE
concentrations are derived from NASA contractor quarterly monitoring data. Trials 12 and 15 were no-detectwellsandweredroppedirom1he
data set.
the reference pump was at the top of the pump and
the inlet screen of the bladder pump was at the
bottom. With this orientation, both pumps
sampled from the same location in the well. A
purge volume of about 1 to 2 liters was drawn
through the reference pump and bladder pump at a
flow rate between 100 to 200 mL/minute.
Following this purge, four replicate samples were
collected with each sampling device.
Chronological Summary of
Demonstration Activities
The demonstration began on Monday, August 9
and concluded on Tuesday, August 17. The first
four days of the demonstration were devoted to
testing those technologies designated "active
samplers." Included in this group were Burge
Environmental (multilevel sampler), Clean
Environment Equipment (bladder pump), Geolog
(bladder pump), QED Environmental (bladder
pump), and Sibak Industries (discrete-level grab
sampler). The second half of the demonstration
was devoted to testing the "passive sampler"
category, of which W. L. Gore (sorbent sampler)
was the only participant. A short briefing was
held on Monday morning for all vendor
participants to familiarize them with the standpipe
facility and the adjacent groundwater monitoring
wells. Standpipe testing began for the active
sampler category at midmorning on Monday and
was completed on the following day. Two days of
testing at the groundwater wells followed. The
passive sampler category tests were begun at the
standpipe Thursday, August 12 and were
completed on Monday, August 16. The passive
sampler category was also deployed at a number
of monitoring well sites simultaneously with
standpipe testing.
Sample analysis was performed in a mobile
laboratory parked near the standpipe and was
carried out concurrently with field-testing. With
the exception of the first day of sample analysis,
all technology and matched-reference samples
were analyzed on the same instrument and usually
12
-------
on the same day. This approach was taken to
minimize the possible influence of instrument
variability on the analysis results.
The demonstration technical team recorded
observations during operation of the devices at the
standpipe and monitoring well trials with regard to
their logistical requirements and ease of use.
These observations also were used to document
any performance anomalies as well as the
technical skills required for operation.
Deviations from the Verification
Plan
Under most field-testing environments,
circumstances often arise that prevent a complete
execution of the test plan. A list of the deviations
from the test plan that are judged to be important
are summarized, along with an assessment of the
resulting impact on the field test data set.
Lost/Dropped Samples—Out of over 800 samples,
1 sample was dropped and lost in the field and 3
were not analyzed either because they were
overlooked or lost in handling by the field
technicians or analysts. Because 4 or 5 replicates
were collected in each sampling trial, the loss of a
few samples does not affect the overall study
results.
QC-Flagged Data—Several samples on the first
day of GC/MS operation were reported with low
internal standard recovery as a result of gas
transfer line problems. A close examination of the
data revealed that these results are comparable
with replicate sample results that passed quality
control (QC) criteria. Consequently, these data
were used in the final analysis. A note indicating
the use of flagged data is included in the
appropriate data tables. No flagged data were
encountered with regard to Well Wizard and
associated reference samples in this study.
Samples Below Quantitation Limit of GC/MS—
One of the wells sampled produced reference and
vendor samples that were at or below the practical
quantitation limit of the GC/MS system. These
data were manually reprocessed by the analyst to
obtain a concentration estimate. Where this
occurs, these data are flagged and appropriate
notice is given in the analysis section of this
report.
Blank GWMonitoring Wells—Six groundwater
monitoring wells were selected for study, based on
preliminary assessment of observed TCE
concentration levels using either historical data or
data from previous onsite well screening activities.
In trials in three wells, well TCE concentration
levels were below the limits of detection, despite
evidence to the contrary from preliminary
screening. Sampler tubing carryover
contamination was determined to be the cause of
the erroneous screening data. One of the "blank"
wells was kept in the data set to assess sampler
blank performance in the field. The other wells
were dropped from the list of trials. The impact
on the overall data set is not important, since the
objective parameters of performance such as
sampler precision and comparability with
reference are derived from the standpipe data.
13
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14
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Section 4 — Performance Evaluation for
Well Wizard Dedicated Sampling System
Introduction
This section briefly discusses the results of test
data analysis and summarizes sampler
performance. Sampler precision, comparability
with reference sample data, and overall versatility
of the sampler for collection of VOC-
contaminated water are discussed. Only summary
data are given in this report. A complete
tabulation of all test data are available from the
authors via individual request. The Model
T1220M and Model T1250 bladder pumps were
used interchangeably in these tests. They are
identical in design and method of operation and
only differ in size. All data are combined and
reported under the term "Well Wizard."
Sampler Precision
The precision for both Well Wizard and the
reference sampler from the first four standpipe
trials is given in Table 5. These four trials
consisted of low (10-20 jjg/L) and high (175-225
|jg/L) target compound concentrations, with
sample collection at shallow (17 feet) and deep (91
feet) locations in the standpipe. Relative standard
deviations are tabulated by compound to give a
total of 24 cases. The final column in the table is
Table 5. Precision Summary for Well Wizard and Reference Sampler
Compound
11DCE
12DCA
BNZ
TCE
112TCA
PCE
Minimum
Maximum
Median
Cone.
Level
Low
Low
High
High
Low
Low
High
High
Low
Low
High
High
Low
Low
High
High
Low
Low
High
High
Low
Low
High
High
Sampling
Depth
(ft)
17
91
17
91
17
91
17
91
17
91
17
91
17
91
17
91
17
91
17
91
17
91
17
91
Well
Wizard
Precision
(%RSD)
13.3
6.0
8.0
5.7
15.3
7.1
5.3
10.6
11.4
4.9
4.6
6.3
9.1
11.9
7.4
3.9
14.7
19.7
13.7
14.0
6.7
12.0
7.4
5.9
3.9
19.7
7.7
REF
Precision
(%RSD)
10.1
8.2
10.6
2.9
30.7
10.6
12.3
5.2
8.6
7.7
9.3
1.1
11.4
7.3
4.2
3.4
5.4
22.7
8.2
9.2
5.3
10.4
6.2
6.7
1.1
30.7
8.2
F-Ratio
1.78
0.36
0.47
3.84
0.23
0.45
0.16
4.01
1.69
0.39
0.20
35.1
0.65
2.31
3.57
1.26
7.74
1.09
3.01
2.38
1.85
1.35
1.76
0.79
F-Ratio
Test
P
0.30
0.83
0.76
0.11
0.91
0.77
0.94
0.10
0.31
0.81
0.93
<0.01
0.66
0.21
0.12
0.41
0.04
0.47
0.16
0.21
0.28
0.39
0.30
0.59
Note: Values ofp less than 0.05 are shown in bold.
REF= Reference.
15
-------
the result of an F-ratio test used to determine
whether the technology and reference sampler
precision can be regarded as statistically
equivalent. The/? value tabulated in the final
column of the table is an estimate of the
probability of encountering the observed
difference in precision, if the assumption is made
that the two groups (technology and reference) are
equivalent. In statistical terms, this is the null
hypothesis and the accompanying assumption is
that only random influences are present and no
systematic bias is present between the two sets of
measurements. Values of p that are close to 1
reflect small differences in precision with a
corresponding high probability of encountering
differences of these magnitudes under the null
hypothesis. On the other hand, values of p less
than 0.05 are indicative of statistically significant
differences that may warrant a rejection of the null
hypothesis. Differences of such magnitude cannot
be satisfactorily explained by random variation
alone in the two sets of data being compared. If
the assumption is made that the two data sets are
from the same population, and only random effects
are occurring, the probability of observing a
difference in two precision values corresponding
to a 0.05 value of p is 5%. For values of p less
than 0.05, it is more likely that some systematic
bias exists between the two sets of data.
The greatest imprecision in Well Wizard and
reference results are encountered for 12DCA and
112TCA, generally at low VOC concentrations
and at both shallow and deep collection points.
Preliminary evaluations of GC/MS method
performance carried out prior to the field
demonstration revealed that these two compounds
had higher analytical uncertainty than the other
target compounds, and it is likely that the higher
uncertainty can be attributed to the analytical
method and not the sampling process. The median
RSD for all compounds in all cases was 7.7% for
the Well Wizard and 8.2% for the reference
samples. Overall, 10 of the Well Wizard RSD
values were more precise than the reference
sampler RSD values and 14 were less precise. An
even, or nearly even, split of technology RSD
values in the greater and less than categories
would suggest equivalence between the two
sampling methods. On a more formal statistical
basis, the results of the F-ratio test shown in the
last column of the table indicate that 2 of the 24
cases had a value ofp that was less than 0.05. The
differences in the other 22 cases can be explained
on the basis of random variation alone. From
these various considerations, the overall precision
of the two sampling methods is judged to be
statistically equivalent.
Sampler Comparability
The comparability of the Well Wizard with
reference data for standpipe trials 1 through 4 is
given in Figure 2 and Table 6, and is expressed as
a percent difference. Percent difference values
were computed for each of the six target
I
III J
_h
Q-20 ug'l S '7H
O-20 uf'LS'91 n
a-200.-g-o. is i? ft
D'200,.g/\. @ Si ft
Figure 2. Well Wizard comparability with reference samples from
the standpipe trials.
16
-------
Table 6. Comparability of Well Wizard and Reference Sample Data
from Stand pipe Trials
Compound
11DCE
12DCA
BNZ
TCE
112TCA
PCE
Minimum
Maximum
Median
Cone.
Level3
Low
Low
High
High
Low
Low
High
High
Low
Low
High
High
Low
Low
High
High
Low
Low
High
High
Low
Low
High
High
Depth
(ft)
17
91
17
91
17
91
17
91
17
91
17
91
17
91
17
91
17
91
17
91
17
91
17
91
Well
Wizard
Difference
(%)
2
-17
-10
0
-3,
1
_7
-4
^2
_1
-10
-3
2
-6
7
^2
2
20
5
1
7
1
12
1
-17
20
1
t-Testb
P
0.82
<0.01
0.12
0.93
0.80
0.84
0.27
0.63
0.78
0.74
0.05
0.90
0.79
0.31
0.13
0.45
0.81
0.18
0.56
0.88
0.10
0.94
0.04
0.87
* The low-level concentration was in the range of 10
compounds. The high-level concentration was in the
to 20 jxg/L for all 6 target
range of 175 to 250 jxg/L.
The t-test was used to compare differences between Well Wizard and reference samples
for each compound in each trial. Small values ofp (<0.05) are shown in bold and are
suggestive of a statistically significant difference. See text for further details.
17
-------
compounds in the four standpipe trials for a total
of 24 cases. The difference values for the Well
Wizard range from -17 to 20%, with a median
value of 1%. The greatest positive difference is
observed for 112TCA at a low concentration and
deep sampling location and the greatest negative
difference is observed for 11DCE at the low
concentration and deep sampling location. The
results for the four 12DCA cases are collectively
closest to 0% difference. Percent difference
values for 12 of the 24 results shown in Table 5
were below 0% with the other 12 values above 0%
and thus are evenly distributed. An even or nearly
even split of percent difference values in the
greater than zero and less than zero categories
suggests equivalence between the two sampling
methods. On a more formal statistical basis, t-test
results show that all but two cases have/? values
that are greater than 0.05. This indicates that in
nearly all test cases, random variation among a
single population can account for the nearly all the
observed differences between Well Wizard and
reference sampling methods. Thus, the presence
of any significant bias in the Well Wizard sampler
can be ruled out relative to the reference sampler.
The Well Wizard comparability data reveal that no
statistically significant negative differences greater
than 17% (11DCE, low concentration, deep
sampling) are observed.
Blank and Clean-Through-Dirty
Test Results
The results of the standpipe trials using blank
solutions show that the Well Wizard samples had
non-detectable levels of all six target compounds.
These results indicate that a new or
decontaminated pump does not measurably
contaminate a clean sample of water.
The Well Wizard pump is designed for permanent
deployment in a single well and is not designed for
multiple deployments at varied depths within a
well. Consequently, this device was not evaluated
in the clean-through-dirty trials at the standpipe.
Monitoring Well Results
Well Wizard results from groundwater monitoring
samples collected at four wells are shown in Table
7 alongside reference data from the same wells.
Four replicate samples were taken with the Well
Wizard and the reference sampler (a submersible
electric gear pump). Relative standard deviations
of both Well Wizard and the reference samples are
given in the table along with the mean percent
difference between the two sets of data. The data
indicate that Well Wizard precision in the field
was generally similar to that observed at the
standpipe (Tables 5 and 7). The percent difference
between the Well Wizard samples and the
reference samples for the high-concentration wells
are both less than 10%. Well Wizard differences
for the low-concentration well (number 12-09) are
very high and may suggest, in light of the good
performance of the Well Wizard at the standpipe,
that the co-located Well Wizard and reference
samplers were not collecting a homogeneous
mixture from the well. The difference may be
further accentuated by the fact that the
concentration levels were near the GC/MS
headspace method detection limit, resulting in
relatively imprecise measurements.
Both the Well Wizard and the reference pump
samples were non-detectable for well number 06-
20, which was known to have no-detect levels of
TCE. These results indicate that the Well Wizard
is not a potential source of contamination in
sampling applications at wells with contaminants
at low concentrations near regulatory limits.
Sampler Versatility
The precision and comparability performance
parameters for the Well Wizard evaluated
previously, indicate that the device can collect
water samples contaminated with VOCs that cover
a range of volatility and solubility (as noted
previously in Section 3), concentration, and
sampling depth with performance characteristics
equivalent to a reference method. Thus, the
sampler is judged to have wide versatility in site
groundwater characterization and monitoring
applications.
Deployment Logistics
The following observations were made during
testing of the Well Wizard at both the standpipe
and groundwater monitoring wells.
• Only one person is needed to operate the
pump and controller. Training requirements
are minimal, with a half-day of training for a
technician to become proficient in routine
field use of the equipment.
• The equipment is self-contained and requires
no external power to operate. The pump
control module is contained in a weatherproof
18
-------
suitcase that includes batteries to power the
microprocessor controller.
The pump is designed for dedicated use in
monitoring wells. The controller and air
source are designed to be moved from
wellhead to wellhead during routine sampling
operations.
The pump is essentially maintenance free,
with few moving parts. The pumps can be
easily serviced in the field by the user, and are
covered by a 10-year warranty against
mechanical failure (excluding chemical
attack).
The pump requires a source of compressed air
or nitrogen. This is supplied by either a
compressed gas bottle or a gasoline- or
electric-powered compressor. Relatively
lightweight (15-pound) compressors or small
compressed air sources are also available to
increase portability.
The pump and controller are designed use with
the newly-released low-flow, minimum well
draw-down sampling protocols that are
designed to minimize the generation of purge
water waste.
Performance Summary
Well Wizard performance is summarized in Table
8. Categories include precision, comparability
with reference method, versatility, and logistical
requirements. Cost and physical characteristics of
the equipment are included.
The results of this verification test show that the
Well Wizard bladder pump and associated
pneumatic controller can be used to collect VOC-
contaminated water samples that are statistically
comparable to a reference method with regard to
both precision and accuracy.
The system is designed for use in well-sampling
programs that incorporate low-volume purge
methodologies. The pumps are optimized for
dedicated placement in monitoring wells that are
included in a routine monitoring program.
Table 7. Well Wizard and Reference Sampler Results from Groundwater Monitoring Wells
Well Number
06-1 1 MW
06-04 MW
12-09MW
06-20 MW
Well Wizard
Average TCE
Concentration
(ng/L)
571
540
16.6
ND (<5)
Well Wizard
Precision
(%RSD)
13.1
7.6
8.7
-
Reference
Average TCE
Concentration
(ng/L)
522
543
6.0
ND (<5)
Reference
Precision
(%RSD)
4.5
11.6
14.3
-
Difference
(%)
9
0
178
-
Note: ND = not detected.
19
-------
Table 8. Performance Summary for Well Wizard Dedicated Sampling System
Performance
Parameter
Precision
Comparability with
Reference Samples
Sampler versatility
Logistical requirements
Completeness
Purchase cost
Size and weight
Other
Summary
For 6 target compounds at low (20 |jg/L) and high (200 |jg/L) concentrations
and at 17-foot and 91-foot sampling depths:
Relative standard deviation range: 3.9 to 19.7% (reference: 1.1 to 30.7%)
Median relative standard deviation: 7.7% (reference: 8.2%)
In 22 of 24 standpipe test cases, Well Wizard precision was statistically
comparable to reference sampler precision.
For 6 target compounds at low (20 |jg/L) and high (200 |jg/L) concentrations
and at 17-foot and 91-foot sampling depths:
Percent difference range: -17 to 20%
Median percent difference: 1%
In 22 of 24 standpipe test cases, Well Wizard differences relative to reference
samples were statistically indistinguishable from 0%.
The Well Wizard demonstrated consistent performance across the tested
range of compound volatility and sampler depth, and is judged to be widely
versatile.
System can be operated by one person with a half-day of training.
System requires a source of compressed air or gas at the wellhead.
System was successfully used to collect all of the samples prescribed in the
test plan.
The system was not used in the optional clean-through-dirty test.
Pump cost: $525 to $650
Pneumatic controller cost: $2,595
Tubing costs: About $3.30 per foot
Model T1220M pump: 1.5-inch dia. x 3.4 foot length
Model T1250 pump: 1.5-inch dia. x 1.3 foot length
Model 400 controller: 18 x 14 x 7.5 inches, 17 pounds
System is designed for low-flow sampling applications.
Pumps are designed for dedicated placement in wells.
Note: Target compounds were 1,1 -dichloroethene, 1,2-dichloroethane, benzene, trichloroethene, 1,1,2-
trichloroethane, and tetrachloroethene.
20
-------
Section 5 — Well Wizard Technology Update
and Representative Applications
Note: The following comments were provided by
the vendor and have not been verified as a part of
this ETV test. They have been edited only for
editorial consistency with the rest of the report.
Well Wizard Sampling System
Types and Configurations
The Well Wizard system is based on a series of
off-the-shelf system components that can be
configured into various system types to meet the
widest range of application needs, including:
• Dedicated sampling pumps with a range of
portable controls and air sources available.
• Portable systems with quick-clean bladder
pump and hose reel.
• Traditional purge-and-sample systems for 3-5
well-volume purging.
• MicroPurge® low-flow sampling systems for
90%+ purge volume reduction.
• "Passive" sampling systems for very low-yield
wells and short water columns.
• Specialized deep-well systems to 1,000-foot
water depth (up to 2,000 feet with extended
intake tubing).
• Sampling system accessories including
MicroPurge flow cells, Sample Pro® water
level meters, Yellow Jacket® interface meters,
and QuickFilter® disposable sample filter
capsules.
In addition to standard configurations, QED
produces custom system components for
specialized sampling application. Contact QED at
800-624-2026 for more information on system
configurations.
System Components
A typical Well Wizard dedicated system consists
of a down-well bladder pump with an inlet screen,
connecting tubing, and a well cap with quick-
connect fittings. To complete the system, a
portable pump controller cycles the pump, and a
driver (compressed gas source) provides the
power.
There are a variety of Well Wizard pumps that
vary by materials of construction, sizes, and flow
rate capabilities. Tubing is twin bonded into a
single line, and is also available in a variety of
materials to meet application requirements. Over
100 different well cap designs are standard, with
customized versions available to match virtually
every type of wellhead completion. Pump controls
can be all-pneumatic designs or electronic versions
with simple digital timer control and well-specific
data storage for up to 500 wells. Drivers include
gasoline-driven air compressor carts, 12-volt direct
current compressors, and compressed gas
cylinders with regulator/hose assemblies. For
details and specifications on Well Wizard system
components contact QED.
New Product Development
QED will soon be releasing a completely new
generation of MicroPurge products to allow
simple, precise control of flow rate, water level
drawdown, and purge completion. The new
products use simple keystroke commands to
achieve expert results. The new products are also
lighter and more compact than any previously
available.
Typical Applications
There are over 50,000 Well Wizard systems
installed throughout the world in a wide variety of
applications. Facilities using the system include:
• Solid waste landfills - commercial and
municipal Resource Conservation and
Recovery Act sites
• Hazardous/radioactive waste disposal facilities
• Military installations - Army, Navy, Air
Force, Marines, Coast Guard, and others
• Department of Energy sites and national
laboratories
• Petroleum refineries, storage and transfer
facilities
• Gasoline stations and other underground
storage tank sites
• Chemical manufacturing plants
• Industrial manufacturing plants
21
-------
• Superfund (Comprehensive Environmental
Response, Compensation, and Liability Act of
1980 or CERCLA) sites
Users' References
QED can provide a list of user references for
specific application types, user groups and
geographic areas. Contact QED for references
specific to your application.
22
-------
Section 6 — References
EPA, 1996. "Test Methods of Evaluating Solid Waste: Physical Chemical Methods; Third Edition; Final
Update III," Report No. EPA SW-846.3-3, Government Printing Office Order No. 955-001-00000-1, Office
of Solid Waste and Emergency Response, Washington, DC.
EPA, 1998. Environmental Technology Verification Report, Field Portable GC-MS, Inficon HAPSITE;
Report Number EPA/600/R-98/142, US EPA, Office of Research and Development, Washington, DC. (also
available at http://www.epa.gov/etv/verifipt.htnrf02).
Foster Wheeler, 1998. "Final Hydrogeologic Investigation Report for the National Aeronautics and Space
Administration Stennis Space Center, Mississippi," Office of Environmental Engineering, NASA, Stennis
Space Center, Mississippi.
Havlicek, L.L, and R D. Grain, 1988a. Practical Statistics for the Physical Sciences, pp. 202-204. American
Chemical Society, Washington, DC.
Havlicek, L.L, and R. D. Grain, 1988b. Practical Statistics for the Physical Sciences, pp. 191-194.
American Chemical Society, Washington, DC.
NIST, 2000. National Institutes of Standards and Technology, Standard Reference Database No. 69, R.
Sander, editor, available at http://webbook.nist.gov/chemistry.
Puls, R.W., and Barcelona, M. J., 1996. Low-Flow (Minimal Drawdown) Ground-Water Sampling
Procedures, US EPA Ground Water Issue (April 1996), Publication No. EPA/540/S-95/504, US EPA Office
Solid Waste and Emergency Response, Washington, DC.
Sandia, 1999. Groundwater Sampling Technologies Verification Test Plan, Sandia National Laboratories,
Albuquerque, NM (also available at http://www.epa.gov/etv/test_plan.htm#monitoring).
23
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24
-------
Appendix A — Reference Pump Performance
Introduction
In addition to the sampling at the standpipe, the verification test design included the collection of vendor
samples from onsite groundwater monitoring wells. During monitoring well sampling, a reference pump was
collocated in the well with the vendor sampler. Both vendor and reference samples were collected
simultaneously to enable a comparison of the results. This appendix summarizes the reference sampler
chosen and outlines its performance and acceptability as a reference sampling technique.
System Description
The reference pump selected for use in this verification study was a submersible electric gear pump (positive
displacement, low-speed pump, Fultz, Model SP-300, Lewistown, PA). Pump construction materials are
stainless steel and polytetrafluoroethylene (PTFE), and pump dimensions are 7.5 inches in length by 1.75
inches in diameter. This pump is a positive displacement device. Water is introduced into the pump through a
60-mesh inlet screen into a stainless steel cavity. Two Teflon gears inside the cavity push the water to the
surface through 100 feet of 'Ainch outside diameter Teflon tubing. An electronic controller is used to
regulate the flow rate of the pump. Nominal sample collection flow rates were in the range of 100-200
mL/min.
Performance Evaluation Method
The gear pump was tested during the standpipe trials in the same manner as the other vendor pumps. Water
samples were collected from the interior of the standpipe in four separate trials with both low (-20 |Jg/L) and
high (-200 |Jg/L) target concentrations at low (17 feet) and high (91 feet) sampling depths (see Section 3 for
additional details). Reference samples were collected from external sampling ports simultaneously with the
pump samples. In each trial, five replicate pump samples and five replicate port samples were collected.
Following collection, all samples were analyzed using the same onsite GC/MS system.
Pump Precision
A summary of pump precision is given in Table A-l. The percent relative standard deviation results for each
of the six target compounds in the four standpipe trials (low concentration—shallow, low concentration-
deep, and so on) for the gear pump and the external sampling port are given in columns 4 and 5, respectively.
The relative standard deviation range for the pump was 3.2 to 16.3%, with a median value of 7.6%. The port
precision data ranged from 2.8 to 16.2%, with a median value of 10.1%. The final column in the table gives
the value ofp associated with the F-ratio test (see Section 3 for a description of this test). Values ofp less
than 0.05 may indicate that significant, nonrandom differences exist between the two estimates of precision.
Out of 24 trials, only 2 show values ofp less than 0.05. These data indicate that pump precision was not
statistically different from the precision obtained from the reference samples taken directly from the standpipe
external ports.
25
-------
Table A-Urecision of Gear Pump and Reference Samples in Standpipe Trials
Compound
11DCE
12DCA
BNZ
TCE
112TCA
PCE
Minimum
Maximum
Median
Cone.
Level
Low
Low
High
High
Low
Low
High
High
Low
Low
High
High
Low
Low
High
High
Low
Low
High
High
Low
Low
High
High
Depth
(ft)
17
91
17
91
17
91
17
91
17
91
17
91
17
91
17
91
17
91
17
91
17
91
17
91
Gear
Pump
Precision
(%RSD)
15.7
3.5
4.0
7.6
15.4
3.2
5.1
6.0
8.1
7.6
3.7
6.1
16.3
5.9
6.4
9.6
9.4
8.4
7.6
11.0
12.9
9.0
4.5
12.7
3.2
16.3
7.6
Port
Precision
(%RSD)
14.2
14.4
8.6
9.7
12.5
13.2
9.0
10.4
11.8
12.9
8.4
9.4
10.5
12.1
2.9
8.6
16.2
15.0
3.5
6.5
9.6
11.7
2.8
8.8
2.8
16.2
10.1
F-Ratio
1.11
14.7
4.81
1.28
2.35
14.1
3.18
2.38
1.71
2.30
5.02
1.83
2.41
3.12
4.82
1.55
3.38
2.81
4.76
3.43
1.36
1.50
2.28
2.38
F-Ratio
P
0.46
0.01
0.08
0.41
0.21
0.01
0.14
0.21
0.31
0.22
0.07
0.29
0.21
0.15
0.08
0.34
0.13
0.17
0.08
0.13
0.39
0.35
0.22
0.21
Pump Comparability with Reference Samples
Gear pump comparability is expressed as the percent difference relative to the reference sample concentration
by subtracting the average reference value from the average gear pump value, dividing the result by the
average reference value, and multiplying by 100. The percent differences for each of the 24 trials are given in
Table A-2. They range from -13 to 14% with a median value of 7%. A t-test for two sample means was used
to evaluate the statistical significance of the differences between the gear pump and reference samples. The
tabulated values ofp give a quantitative measure of the significant of the observed difference in probabilistic
terms. Values of p less than 0.05 suggest that a statistically significant bias may exist for the trial. With five
exceptions, all values ofp are greater than 0.05, indicating that overall, the differences between the two
sampling methods are statistically indistinguishable.
26
-------
Table A-2. Comparability of the Gear Pump with the Reference
Samples in Standpipe Trials
Compound
11DCE
12DCA
BNZ
TCE
112TCA
PCE
Minimum
Maximum
Median
Cone.
Level3
Low
Low
High
High
Low
Low
High
High
Low
Low
High
High
Low
Low
High
High
Low
Low
High
High
Low
Low
High
High
Depth
(ft)
17
91
17
91
17
91
17
91
17
91
17
91
17
91
17
91
17
91
17
91
17
91
17
91
Difference
(%)
-4
7
-3
13
24
10
-2
12
11
13
0
14
0
16
0
11
-6
7
1
10
-13
6
-6
6
-13
24
6.5
t-Tesf
P
0.64
0.31
0.54
0.05
0.05
0.13
0.71
0.06
0.13
0.11
0.98
0.03
0.99
0.04
0.95
0.10
0.51
0.41
0.77
0.15
0.08
0.37
0.03
0.42
1 The low-level concentration was in the range of 10 to 20 (xg/L for all 6 target
compounds. The high-level concentration was in the range of 175 to 250
b The t-test was used to compare differences between the gear pump and reference
samples for each compound in each trial. Small values ofp (O.05) are shown in bold and
are suggestive of a statistically significant difference. See text for further details.
27
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The percent recovery data for the gear pump are also shown graphically by target compound in Figure A-l for
each of the four standpipe trials. Fifteen of the 24 percent difference values are in the positive percent
difference range, suggesting that many of the samples collected with the gear pump contained higher
concentrations than those samples collected from the corresponding external sampling port. An exhaustive
evaluation of the data was not performed to characterize this phenomenon; however, it is possible that this
was a result of bias in the analytical method, since one would not expect sample losses to be significant in the
reference sampling procedure.
25
20
10
S 5
o •-
-10
H~20ng/L@17ft
Q-200 ng/L @ 91 f
E~20ng/L@17ft
O-200 lig/L <8) 91 f
11DCE 12DCA BNZ TCE
Compound
112TCA
PCE
Figure A-l. Percent recoveries of the reference pump by compound for the four
standpipe trials.
Reference Pump Performance Summary
The test data for the reference pump reveal considerable variability for PCE and 12DCA. However, the
variability and comparability for TCE, the only compound encountered in the field trials, are acceptable. The
mean relative standard deviation for TCE at concentration levels ranging from 20 to 200 |jg/L was 9.6% and
the mean percent difference for TCE in the same concentration range was 7%. The data presented for TCE
show that the pump is equivalent to the reference sampling method in terms of both precision and accuracy
and is acceptable for use as a reference standard.
28
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Appendix B — Quality Summary for Analytical Method
Introduction
An onsite GC/MS-headspace method was chosen for analysis of all samples in this study. Two identical
GC/MS systems were operated by Field Portable Analytical (Folsom, CA) using a modified EPA Method
8260 (for a summary of the method, see Section 3). Data quality measures were incorporated into all onsite
analyses consistent with the guidelines in Method 8260. This appendix summarizes those data quality
measures, thereby demonstrating the adequacy of the method for this verification study.
Data Quality Measures
A number of data quality measures were used to verify acceptable instrument performance and the adequacy
of the final analytical results throughout the course of the study. These measures are summarized in Table
B-l. All data quality measures in this table were followed, with the exception of duplicates. Duplicates were
not routinely run since all of the samples from the field were in batches of replicates. Earlier prefield
demonstration studies indicated that the field replicates were the same in composition so that they could be
treated as analysis duplicates.
Table B-l. Onsite GC/MS-Headspace Method Quality Control Measures
Quality Control
Check
MS tune check w/
bromofluorobenzene
(BFB)
5-Point (Minimum)
calibration
Continuing calibration
check (CCC)
End calibration
checks
Duplicates
Method blanks
Minimum
Frequency
Every 12 hours
Beginning of each day
Beginning of each day
End of each day
10% of the samples
After beginning of day
CCC
Acceptance
Criteria
Ion abundance criteria
as described in EPA
Method TO-1 4
%RSD < 30%
+ 25% difference of
the expected
concentration
for the CCC
compounds
+ 25% RPDofthe
beginning CCC
Relative percent
difference < 30%
Concentrations for all
calibrated compounds
< practical
quantification level
Corrective
Action
1) Reanalyze BFB
2) Adjust tune until
BFB meets
criteria
Rerun levels that do
not meet criteria
1) Repeat analysis
2) Prepare and run
new standard
from stock
3) Recalibrate
1) Repeat analysis
2) If end check is
out, flag data
for that day
1) Analyze a third
aliquot
2) Flag reported
data
Rerun blanks until
criteria are met
Data Quality Examples
The following data are examples of system performance throughout the course of the study. In the interest of
brevity, all quality control data are not shown in this appendix. A complete tabulation of all quality control
data is included in the GW SAMPLING DATA NOTEBOOK and is available for viewing through a request
to the ETV Site Characterization and Monitoring Technologies Pilot Manager.
29
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Method Blank Check
Method blanks were run at the beginning of each 12-hour analysis session. Concentration levels of the six
target compounds were reported as ND <5 |jg/L for all method blank samples.
Continuing Calibration Check
The method criterion for the continuing calibration checks run at the beginning and end of each analysis cycle
was a value within 25% of the expected value. The results of the TCE continuing calibration checks for both
of the GC/MS instruments used in the study are shown in Figures B-l and B-2. Similarly, the results of the
PCE continuing calibration check for both instruments are shown in Figures B-3 and B-4. All check
compound recoveries fall within the predefined control interval of 70 to 130%. The control interval is
specified in EPA Method SW-846, from which this method is adapted. The relative percent differences
between the pre- and post-analysis batch calibration check samples are shown in Figure B-5. In two cases,
the relative percent difference falls outside the 25% window. Data from these days were not rejected,
however, since the ±30% criteria for the calibration check was met.
GCMS (Pepe) Control Chart
TCE Check Standard
130
& 110
Upper Control Limit
Lower Control Limit
8/10/99 8/11/99 8/12/99 8/13/99 8/14/99 8/15/99 8/16/99 8/17/99
Day
Figure B-l. Calibration check control chart for TCE on GC/MS #1.
30
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130
120
110
100
!
6
GCMS (Taz) Control Chart
TCE Check Standard
Upper Control Limit
D
Lower Control Limit
n
8/9/99 8/10/99 8/11/99 8/12/99 8/13/99 8/14/99 8/15/99 8/16/99 8/17/99
Day
Figure B-2. Calibration check control chart for TCE on GC/MS #2.
GCMS (Pepe) Control Chart
PCE Check Standard
s?
o
8
a:
Standard
i l
1
6
RD -
Upper Control Limit
4Se
«Se
riesl
ries2
*»«,*,
D ;
1 l
_* f____
Lower Control Limit
. ..A.. .
8/10/99 8/11/99 8/12/99 8/13/99 8/14/99 8/15/99 8/16/99 8/17/99
Day
Figure B-3. Calibration check control chart for PCE on GC/MS #1.
31
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140
GCMS (Taz) Control Chart
Upper Control Limit
ss
> 110
Lower Control Limit
8/9/99 8/10/99 8/11/99 8/12/99 8/13/99 8/14/99 8/15/99 8/16/99 8/17/99
Day
Figure B-4. Calibration check control chart for PCE on GC/MS #2.
GC/MS (Pep* and Taz) System Check
Relative Percent Difference -- Daily Begin/End Chech
40
fe
o
20
fS
&
QPcpe-TCE
DPepe-PCE
QTar-TCE
B Taz-PCE
_
r 3
1 \\
»,.,, ;, I.,),;,,.,., f.'l'.'ji ,-; I/,'-i"' c. !>•*/' h.'i'-i1-, ?•',':""'
Analysis Date
Figure B-5. GC/MS system check relative percent differences.
32
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