United States Office of Research and EPA/600/R-00/078
Environmental Protection Development August 2000
Agency Washington, D.C. 20460
vvEPA Environmental Technology
Verification Report
Groundwater Sampling
Technologies
Clean Environment Equipment
SamplEase® Bladder Pump
Sandia
National
Laboratories
ETV ETV ET
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THE ENVIRONMENTAL TECHNOLOGY VERIFICATION
PROGRAM
laboratories
ETV JOINT VERIFICATION STATEMENT
TECHNOLOGY TYPE: GROUND WATER SAMPLING TECHNOLOGIES
APPLICATION: VOC-CONTAMINATED WATER SAMPLING
TECHNOLOGY NAME: SamplEase Bladder Pump - Model SP15T36
COMPANY: Clean Environment Equipment
ADDRESS: 1133 Seventh St. PHONE: (510) 891-0880
Oakland, CA 94607 FAX: (510) 444-6789
WEBSITE: www.cee.com
EMAIL: service(5)cee.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 Technologies 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 SamplEase
bladder pump and pneumatic controller manufactured by Clean Environment Equipment.
EPA-VS-SCM-42 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 technologies 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 VOC compounds 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 SamplEase bladder pump, 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 sites with VOC-contaminated groundwater at the NASA Stennis facility. The technologies
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: Clean Environment Equipment,
SamplEase Bladder Pump, EPA/600/R-00/078.
TECHNOLOGY DESCRIPTION
The SamplEase is a bladder pump consisting of an internal flexible Teflon bladder that is positioned within
a rigid stainless steel pump body. The ends of the pump are also constructed of Teflon. 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 desired sample flow rate at the wellhead. The bladder design offers
EPA-VS-SCM-42 The accompanying notice is an integral part of this verification statement. August 2000
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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.
Clean Environment Equipment offers a line of bladder pumps manufactured with various materials. The
pump tested during this evaluation was the Model SP15T36, which uses polytetrafluoroethylene (Teflon)
for the bladder and 316 stainless steel for the pump body, fittings, and intake screen. The pump and intake
screen is 40 inches long. The pump diameter is 1.5 inches and its weight is 3.8 pounds. The pump has a
maximum lift capacity of 500 feet, and flow rates are adjustable from less than 100 mL/min to over 5
L/min, depending on pump depth. The pump can draw samples from greater depths using an extended
intake attached to the inlet of the pump.
The Model SC250 controller is a mechanical controller used to regulate the flow of compressed nitrogen,
obtained from a cylinder at the wellhead, to the bladder pump. The controller is weatherproof and is
packaged in a durable case that can be easily hand carried. The controller has overall dimensions of 10 x 9
x 7 inches and a weight of 9.8 pounds. Drive air for the bladder pump can be delivered from compressed
gas cylinders or from a field-portable gasoline- or electric-powered compressor.
The bladder pump's list price is $630 and the controller lists at $1,550. An optional inlet screen is priced at
$50. Teflon-lined polyethylene dual tubing is also a requirement for most VOC sampling applications and
is priced at $1.30 per foot.
VERIFICATION OF PERFORMANCE
The following performance characteristics of the SamplEase bladder pump were observed:
Precision: The precision of the sampler was determined through the collection of a series of replicate
samples from 3 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 18 cases. SamplEase
bladder pump precision, represented by the relative standard deviation, for all compounds at all
concentrations and sampling depths evaluated in this study, ranged from 5.1 to 24.2%, with a median
value of 11.7%. In 12 cases the relative standard deviation of the SamplEase bladder pump was greater
than the reference, with SamplEase bladder pump precision less than or equal to reference sample
precision in the other 6 cases. The F-ratio test was used to assess whether the observed precision
differences were statistically significant. Test results showed that precision differences between the
SamplEase bladder pump and reference samples were statistically insignificant at the 95% confidence
level in 16 of 18 cases.
Comparability with a Reference: SamplEase bladder pump results from the standpipe trials were
compared with results obtained from reference samples collected at the same time. Both SamplEase 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 VOC compounds at all concentrations and sampler depths in this study ranged
from -16 to 31%, with a median difference of-5%. The t-test for two sample means was used to assess
whether the differences between SamplEase bladder pump and reference sample results were statistically
significant. These tests showed that in 13 of 24 trials, differences were statistically indistinguishable
from 0% at the 95% confidence level. In the remaining 5 cases, statistically significant negative bias was
not in excess of 16%.
Versatility: Sampler versatility is the consistency with which the sampler performed over the range of
target compound volatility, concentration level, and sampling depth. SamplEase bladder pump
performance did not vary with changes in compound, concentration, or sampler depth. Thus, the
SamplEase bladder pump is regarded as a widely versatile sampling device and applicable for sampling
the types of VOCs likely to be encountered under actual field conditions.
EPA-VS-SCM-42 The accompanying notice is an integral part of this verification statement. August 2000
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Logistical Requirements: The sampler can be deployed and operated in the field by one person. One
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 SamplEase bladder pump is designed for dedicated use in a single
monitoring well and is not intended for repeated deployment and retrieval in a series of wells.
Overall Evaluation: The results of this verification test show that the SamplEase bladder pump and
associated pneumatic controller can be used to collect VOC-contaminated water samples that are
generally statistically comparable to reference samples when analyzed with the sample 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-42 The accompanying notice is an integral part of this verification statement.
August 2000
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EPA/600/R-00/078
August 2000
Environmental Technology
Verification Report
Groundwater Sampling
Technologies
Clean Environment Equipment
SamplEase Bladder Pump
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 reviewed 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 ivv
Acknowledgments v
Abbreviations and Acronyms vi
1 INTRODUCTION 1
Background 1
Demonstration Overview 1
2 TECHNOL OG Y DESCRIPTION: CLEAN ENVIRONMENT EQ UIPMENT SAMPLEASE BLADDER PUMP... 3
3 DEMONSTRATION PROCESS AND DESIGN 5
Introduction 5
Site Description 5
Verification Test Design Summary 7
Test Design Elements 7
Sampler Performance Parameters 9
Sample Analysis 10
Data Processing 10
Data Quality Control 11
Verification Test Plan 11
Standpipe and Groundwater Well-Sampling Matrix 11
Chronological Summary of Demonstration Activities 13
Deviations from the Verification Plan 13
4 PERFORMANCE EVALUATION FOR SAMPLEASE BLADDER PUMP 15
Introduction 15
Sampler Precision 15
Sampler Comparability 16
Blank and Clean-Through-Dirty Test Results 17
Monitoring Well Results 17
Sampler Versatility 19
Deployment Logistics 19
Performance Summary 19
5 SAMPLEASE BLADDER PUMP TECHNOLOGY UPDATE AND REPRESENTATIVE APPLICATIONS 21
6 REFERENCES 22
APPENDICES
A: REFERENCE PUMP PERFORMANCE 23
B: QUALITY SUMMARY FOR ANALYTICAL METHOD 27
ill
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List of Figures
1 The standpipe at the USGS Hydrological Instrumentation Facility 6
2 SamplEase comparability with reference samples from the standpipe trials 17
A-l Percent recoveries of the reference pump by compound for the four standpipe trials 26
B-l Calibration check control chart for TCE on GC/MS #1 28
B-2 Calibration check control chart for TCE on GC/MS #2 29
B-3 Calibration check control chart for PCE on GC/MS #1 29
B-4 Calibration check control chart for PCE on GC/MS #2 30
B-5 GC/MS system check relative percent differences 30
List of Tables
1 Construction Details of Groundwater Monitoring Wells 7
2 Target VOC Compounds 8
3 Sampler Verification Trials at the Standpipe 12
4 Sampler Verification Trials at the Groundwater Monitoring Wells 12
5 Precision Summary for SamplEase and Reference Sampler 16
6 Comparability of SamplEase and Reference Sampler Data from Standpipe Trials 18
7 SamplEase and Reference Sampler Results from Groundwater Monitoring Wells 19
8 Performance Summary for SamplEase 20
A-l Precision of Gear Pump and Reference Samples in Standpipe Trials 24
A-2 Comparability of the Gear Pump with the Reference Samples in Standpipe Trials 25
B-l Onsite GC/MS-Headspace Method Quality Control Measures 27
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@sandia.gov
(702) 798-2432 (v)
E-mail: koglin.eric@epa.gov
For more information on the Clean Environment Equipment SamplEase bladder pumps, contact
Michael Breslin
Clean Environment Equipment
1133 Seventh Street
Oakland, CA 94607
800-537-1767 (v)
E-mail: m.breslin(5),cee.com
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Abbreviations and Acronyms
BNZ
DIFF
EPA
ETV
GC/MS
fflF
MSL
MW
NASA
ND
NERL
PCE
PTFE
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
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 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
(multi-level sampler, Burge Environmental,
Tempe, AZ), Well Wizard dedicated sampling
system (bladder pump, QED Environmental, Ann
Arbor, MI), Micro-Flo (bladder pump, Geolog
Inc., Medina, NY), Kabis sampler (discrete-level
grab sampler, Sibak Industries, Solano Beach,
CA), GoreSorber (diffusional sampler, W. L. Gore
and Associates, Elkton, MD), and the SamplEase
bladder pump (Clean Environment Equipment,
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Oakland, CA). This report contains an evaluation
of the SamplEase bladder pump.
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 wels 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, and reference samples were collected
for comparison with each sampling device. The
principal contaminant at the site was
trichloroethene (TCE).
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 SamplEase
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. 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: Clean Environment
Equipment SamplEase Bladder Pump
This section provides a general description and
overview of the capabilities of the Clean
Environment Equipment SamplEase bladder
pump. The information used to prepare this
section was provided by Clean Environment
Equipment.
The bladder pump consists of an internal flexible
polytetrafluoroethylene (Teflon) bladder that is
positioned within a cylindrical pump body of
Teflon and stainless steel. The ends of the pump
are equipped with one-way inlet and outlet valves.
The pump passively fills with water when the pump
is at depth by virtue of the 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
compresses 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.
Clean Environment Equipment offers a line of
bladder pumps manufactured with various
materials. The pump tested during this evaluation
was the SamplEase Model SP15T36. The pump is
40 inches in length when an intake screen is
attached, 1.5 inches in diameter, and weighs 3.8
pounds. The pump uses Teflon for the bladder
material and 316 stainless steel for the pump body,
fittings, and intake screen. The pump has a
maximum lift capacity of 500 feet, and flow rates
are adjustable from less than 100 mL/min to over 5
L/min, depending on the pressure head.
The Model SC250 controller is a mechanical
controller used to regulate the flow of compressed
air or nitrogen, obtained from a cylinder at the
wellhead, to the bladder pump. The controller is
weatherproof and is packaged in a durable case that
can be hand carried. The controller has overall
dimensions of 10 x 9 x 7 inches and a weight of 9.8
pounds. Drive air for the bladder pump can be
delivered from compressed gas cylinders or from a
field-portable gasoline- or electric-powered
compressor.
The bladder pump list price is $630 and the
controller list price is $1,550. An optional stainless
steel pump inlet screen is priced at $50. Teflon-
lined polyethylene dual tubing is also a requirement
for most VOC sampling applications and is priced
at $1.30 per foot.
The Clean Environment Equipment bladder pump
systems are designed for dedicated well-sampling
applications. The bladder pump and tubing are left
in the well and the controller and drive air source
are moved from well to well during typical
sampling operations.
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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 Hydrologic
Instrumentation 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 the 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, and found
at elevations ranging from 10 to 30 feet mean sea
level (MSL). These overlay a sandy unit named
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 interbedded 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.
-------
B IN. OlA.
SPI 4
5P13
SP11
SPIO
SP9.
i*
SP5
SP2
•HOLDING TANKS
FLOATIM6 TOP
LEVEL 5
-1 IN, D1A. FILL/DRAIN L1IC
LEVEL 4
LEVEL 3
5P - SAMPLINS PORT
SP DISTANCE FROM TIM5 WATER LEVEL
5P13 17.5 ft.
SPi 5-4 Ft.
SP? G4 ft.
SP4 82 Ft.
SP2 92 Ft,
LEVEL 2
/EXIT LINE
Figure 1. The stand pipe at the USGS Hydrological Instrumentation Facility.
-------
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
polyvinyl chloride (PVC) pipe with a 10-foot PVC
screen length. All samples were collected at the
midscreen 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 VOC Compounds—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
-62.8
-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
-0.4
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 2. Target VOC Compounds
Compound
Tetrachloroethene (PCE)
1,1-Dichloroethene(11DCE)
Trichloroethene (TCE)
Benzene (BNZ)
1 ,2-Dichloroethane (12DCA)
1,1,2-Trichloroethane
(112TCA)
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
1 Henry's constant data fromNIST, 2000.
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 sample collection
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 for the overlying contaminated
layers in the well. Not all vendors participated in
this part of the study.
Ground-water Well Reference Samples—Sixonsite
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 collocated in the well with the sampling
devices under test in order to obtain simultaneous
reference samples from the well. Teflon tubing
(Vi-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
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:
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 the assessment of sampler
precision, a statistical test was used 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 Xta± the average reported concentration
of all technology sample replicates and X,,f 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 method.
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 final 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, HAP SITE, 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 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
10
-------
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
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
under refrigeration temperatures to Field Portable
Analytical. The samples were analyzed using the
headspace GC/MS 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 with
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 grab samplers.
11
-------
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 the sample
was 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 they were at no-detect levels for TCE.
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 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.
Table 3. Sampler Verification Trials at the Standpipe
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 ug/L)
Low (-20 pg/L)
High (-200 |_ig/L)
High (-200 pg/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 simultaneously with the device samples from
adjacent external standpipe sampling ports. Sample collection points during trials 6 and 7 were from the low VOC
concentration region after the sampler was lowered through a high VOC concentration region.
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-inch and 4-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-detect wells and were dropped from the data set.
12
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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
interval 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 groundwater wels
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 carried out 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
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, and this test was no
exception. 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 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 SamplEase bladder
pump 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 three trials, well TCE concentration levels were
below the limits of detection, despite evidence to
the contrary from preliminary screening. Sampler
contamination during preliminary screening
carried out prior to the field test was determined to
be the cause of erroneously high readings. 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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Open Fill Valve at Standpipe—A fill valve was
inadvertently left open while the SamplEase pump
was being used to collect low-concentration
samples from the deep location during trial 2.
This open valve resulted in the collection of
SamplEase and reference samples with differing
VOC compositions. This procedural anomaly was
discovered subsequent to the test during data
analyses and thus could not be remedied. These
suspect data were deleted from the data set. The
remaining data provide an adequate sample size
for evaluating SamplEase bladder pump
performance, although evaluation at low VOC
concentration and deep collection depth was not
possible.
14
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Section 4 — Performance Evaluation for
SamplEase Bladder Pump
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.
Sampler Precision
The precision for both SamplEase and reference
samples from the first four standpipe trials is given
in Table 5. The results are listed by the six
compounds for 3 test conditions (low
concentration at shallow sampling depth, high
concentration at shallow sampling depth, and so
on), for a total of 18 cases.1 Included in the table
are the standard deviations of the SamplEase
bladder pump and reference method. The final
column in the table is the result of an F-ratio test
used to determine whether the technology and
reference precision can be regarded as statistically
different. The p 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 of measurements (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 in the
two sets of measurements. Values ofp that are
close to 1 reflect small differences in precision
with a corresponding high probability of
encountering differences of this magnitude under
the null hypothesis. On the other hand, values of p
that are less than 0.05 are indicative of larger
Six cases from the low concentration, deep sampling
point were deleted from the standpipe trial data set.
The data were rejected because of an obvious mismatch
between SamplEase and reference samples caused by
an open valve at the base of the standpipe. The
SamplEase and reference samples were from different
mixtures and were not comparable. This experiment
procedural error was not noted until after the field trials
were completed and thus could not be remedied.
precision 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%. In other words, such a difference would be
highly unlikely. For values ofp less than 0.05, it
is more likely that some systematic bias exists
between the two sets of data.
The greatest imprecision in the SamplEase bladder
pump results are encountered for 12DCA and
112TCA at the high VOC concentrations and the
shallow collection depth (Table 5). Preliminary
evaluations of GC/MS performance carried out
prior to the field demonstration revealed that these
two compounds had higher analytical uncertainty
than the other target compounds, so this effect can
be attributed to the analytical method and not the
sampling process. The median RSD for all
compounds in all trials was 11.7% for the
SamplEase bladder pump and 10.7% for the
reference samples. In 12 of the 18 cases shown in
the table, the SamplEase pump precision was
worse than the reference sample precision with the
remaining cases having precision better than or
equal to the reference sample precision. An even
or nearly even split of technology precision in the
greater-than and less-than categories would
suggest equivalence between the two sampling
methods. Qualitatively, the indications are that the
SamplEase bladder pump is less precise than the
reference method. On a more formal statistical
basis, the F-ratio test results shown in the last
column of Table 5 reveal that 2 of 18 cases had a
value of p that was less than 0.05. Thus,
differences in precision between SamplEase pump
samples and reference samples are statistically
insignificant in 16 of the 18 cases. Overall, the
conclusion can be made that the SamplEase and
reference sample sets are comparable in terms of
precision.
15
-------
Table 5. Precision Summary for SamplEase Bladder Pump 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
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
SamplEase
Precision
(%RSD)
6.6
No data
12.1
10.4
18.2
No data
17.8
11.6
5.1
No data
16.4
11.7
7.4
No data
13.2
7.9
12.7
No data
24.2
6.9
8.4
No data
12.2
7.7
5.1
24.2
11.7
REF
Precision
(%RSD)
15.2
No data
12.4
8.0
13.4
No data
12.1
6.2
9.9
No data
11.5
6.7
12.4
No data
5.8
4.6
12.9
No data
5.9
6.5
14.4
No data
5.7
4.1
4.1
15.2
10.7
F-Ratio
4.62
No data
1.61
1.40
1.59
No data
3.66
2.76
3.32
No data
3.04
2.60
2.94
No data
6.82
2.32
1.27
No data
24.72
1.11
3.45
No data
5.03
2.48
F-Ratio
Test
P
0.08
No data
0.32
0.38
0.33
No data
0.12
0.17
0.14
No data
0.15
0.19
0.16
No data
0.04
0.22
0.41
No data
<0.01
0.46
0.13
No data
0.07
0.20
Notes: Values of p less than 0.05 are shown in bold. REF = Reference. See text for explanation regarding missing
values.
Sampler Comparability
The comparability of the SamplEase bladder pump
with reference data for the standpipe trials is given
in Figure 2 and Table 6. Percent difference values
were computed for each of the six target
compounds in the three valid standpipe trials for a
total of 18 cases. The percent difference values
for the SamplEase bladder pump range from -16
to 31%, with a median value of-4.5%. Average
difference values for 8 of the 18 cases were above
0%, with the other 10 cases below 0%. An even
or nearly even split of percent difference values in
the greater than zero and less than zero categories
would be indicative of equivalence between the
two sampling methods. In this case the split is
nearly even giving qualitative evidence of
comparability. On a more formal statistical basis,
t-test results show that all but 5 of the 18 cases
have p values greater than 0.05. This indicates
that in many cases, random variation among a
single population can account for the observed
differences between the SamplEase bladder pump
samples and the reference samples. Thus, the
presence of any significant SamplEase bladder
pump bias can be ruled out relative to the
reference method.
The SamplEase bladder pump data reveal that no
statistically significant negative differences in
excess of -16% (PCE, high concentration, deep
sampling) are observed. Although positive
differences of greater magnitude are observed,
they are judged with less concern since loss of
VOCs in the sampling process is expected to be
the primary factor influencing sampler
performance.
16
-------
H~20 ng/Lat 17ft
Il~20 ng/L at 91 ft (NO DATA)
D-200 Mg/Lat 17ft
Il~200 uq/L at 91 ft
11DCE 12DCA BNZ TCE
Compound
112TCA
PCE
Figure 2. SamplEase bladder pump sample comparability with reference samples from
the standpipe trials.
Blank and Clean-Through-Dirty
Test Results
The results from the standpipe trials using blank
solutions show that both the SamplEase and
reference 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 SamplEase bladder pump is designed for
permanent deployment in a single well and is not
recommended for movement from well to well.
Consequently, the vendor chose not to participate
in the clean-through-dirty tests.
Monitoring Well Results
SamplEase bladder pump results from
groundwater monitoring samples collected at four
wells are shown in Table 7 alongside reference
sample data from the same wells. Four replicate
samples were taken with the SamplEase bladder
pump and the reference sampler (a submersible
electric gear pump). Relative standard deviations
of both SamplEase and the reference samples are
given in the table along with the mean percent
difference between the two sets of data. The
observed relative standard deviations indicate that
SamplEase precision in the field was generally
similar to that observed at the standpipe.
SamplEase bladder pump differences compared to
reference samples for the high-concentration wells
are both less than 8%. SamplEase bladder pump
differences for the low-concentration well
(number 12-09) are very high and may suggest, in
light of the good performance of the SamplEase
bladder pump at the standpipe, that the co-located
SamplEase 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.
17
-------
Table 6. Comparability of SamplEase Bladder Pump and Reference
Sample Data from 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
SamplEase
Difference
(%)
7
No datac
31
-9
-7
No data
31
-10
7
No data
22
-8
-2
No data
15
-12
-10
No data
20
-10
-8
No data
5
-16
-16
31
-4.5
t-Testb
(P)
0.35
No data
<0.01
0.12
0.47
No data
0.03
0.09
0.21
No data
0.07
0.21
0.77
No data
0.08
0.01
0.23
No data
0.16
0.03
0.32
No data
0.41
<0.01
a The low-level concentration was in the range of 10 to
high-level concentration was in the range of 175 to 250
20 |ig/L for all 6 target compounds. The
jig/L.
b The t-test was used to compare the mean percent difference of the SamplEase bladder pump
samples relative to the reference samples for each compound in each trial. Small values ofp
(<0.05) shown in bold are suggestive of sampler bias. See text for further details.
0 During data analysis following the test, it was discovered that a fill valve was inadvertently left
open during a port ion of SamplEase pump testing. As a result, SamplEase and reference samples
were different. The data from this trial were dropped from the data set used in the analysis.
18
-------
Table 7. SamplEase and Reference Sampler Results from Groundwater Monitoring Wells
Well
Number
06-1 1MW
06-04MW
12-09MW
06-20MW
Well
Numb
er
06-11
06-04
12-09
06-20
SamplEase
Average TCE
Concentration
(ng/L)
485
682
11.9
ND (<5)
SamplEase
Precision
(%RSD)
4.6
12.1
46.1
-
Reference
Average TCE
Concentration
(ng/L)
479
633
21.2
ND (<5)
Reference
Precision
(%RSD)
4.6
4.5
20.3
-
SamplEase
Difference
(%)
1
8
-44
-
Note: ND = not detected.
Both the SamplEase and the reference pump
samples were non-detectable for the well with no
TCE. These results indicate that the SamplEase
bladder pump is not a potential source of
contamination in low-level sampling operations.
Sampler Versatility
The performance parameters for the SamplEase
bladder pump discussed previously indicate that
the device can collect water samples contaminated
with VOCs of varying volatility, concentration,
and sampling depths with acceptable performance.
In almost all test cases, SamplEase bladder pump
samples were not statistically different from
reference samples with regard to precision. In
comparison with reference samples, most
SamplEase results were within ±20% difference.
Based on these considerations, the SamplEase
bladder pump is judged to have wide versatility in
site groundwater characterization and monitoring
applications.
Deployment Logistics
The following observations were made during
testing of the SamplEase bladder pump 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 day of training required
for a technician to become proficient in
routine field use of the equipment.
• The pump and controller are both compact and
require no external power to operate. The
pump control module is contained in a small
lightweight weatherproof enclosure.
• The pump requires a source of compressed air
or nitrogen supplied by either a compressed
gas bottle or a gasoline- or electric-powered
compressor. These accessories are heavy and
required additional effort to transport and
operate at the wellhead.
• 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 bladder pump itself is not
well suited for moving from well to well
during routine well monitoring operations
since this movement requires that the pump be
decontaminated and that new tubing (or
decontaminated tubing) be used with each new
deployment.
• The pump is essentially maintenance free,
with few moving parts. Pump failure is
usually remedied by complete replacement as
opposed to a more costly repair option. Clean
Environment Equipment offers a 10-year
warranty for pumps that are equipped with
intake screens.
• The pump can be used with the EPA low-flow,
low-volume-purge sampling protocol.
Performance Summary
SamplEase bladder pump performance is
summarized in Table 8. Evaluation categories
include precision, comparability with a reference,
versatility, and logistical requirements. Cost and
physical characteristics of the equipment are also
included. The results of this verification test show
that the SamplEase bladder pump and associated
pneumatic controller can be used to collect VOC-
contaminated water samples that are generally
statistically comparable to a reference method with
regard to both precision and comparability. The
SamplEase bladder pump system is well suited for
use in well-sampling programs that incorporate
low flow sampling and low-volume purge
sampling protocols. The pumps are optimized for
dedicated placement in monitoring wells that are
included in a routine monitoring program.
19
-------
Table 8. Performance Summary for SamplEase Bladder Pump
Performance
Parameter
Summary
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:
Relative standard deviation range: 5.1 to 24.2% (reference: 4.1 to 15.2%)
Median relative standard deviation: 11.7% (reference: 10.7%)
In 16 of 18 standpipe test cases, SamplEase pump precision was statistically
comparable to the reference sampler precision
(See note in "Other" category)
Comparability with
Reference Samples
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: -16 to 31%
Median percent difference: -5%
In 13 of 18 standpipe test cases, SamplEase pump differences relative to
reference samples were statistically indistinguishable from 0%.
(See note in "Other" category)
Sampler versatility
The SamplEase pump demonstrated consistent performance across the
tested range of compound volatility and sampler depth, and is judged to be
widely versatile.
Logistical requirements
System can be operated by one person with a day of training.
System requires a source of compressed air or nitrogen at the wellhead.
Completeness
System was successfully used to collect all of the samples prescribed in the
test plan.
Purchase cost
Model SP15T36 pump: $630
Inlet screen: $50
Model SC250 pneumatic controller: $1,550
Teflon-lined poly tubing costs: $1.30 per foot
Size and weight
Model T1220M pump: 1.5-inch dia. x 40-inch length (with intake screen), 3.8
pounds
Model SC250 controller: 10x9x7 inches, 9.8 pounds
Other
System is designed for low-volume purge applications.
Pumps are optimized for dedicated placement in wells.
Comparison at low VOC concentration and deep collection depth could not be
done as a result of missing reference data caused by an experimental
procedural error that was not attributable Clean Environment Engineering
personnel.
Note: Target compounds were 1,1-dichloroethene, 1,2-dichloroethane, benzene, trichloroethene, 1,1,2-trichloroethane, and
tetrachloroethene.
20
-------
Section 5 — SamplEase Bladder Pump Technology Update
and Representative Applications
Note: The vendor chose not to submit any
material for this section.
21
-------
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/verifrpt.htm#02).
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).
22
-------
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 (PFTE), 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 PFTE gears inside the cavity push the water to the
surface through 100 feet of 'Ainch outside diameter PFTE 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.
23
-------
Table A-l. Precision 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 24% 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.
24
-------
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
Differenc
(%)
-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
7
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
The high-level concentration was in the range of 175
to 20 jxg/L for all 6 target compounds.
to 250 ng/L.
b The t-test was used to compare differences between SamplEase pump and reference
samples for each compound in each trial. Small values of p (<0.05) are shown in bold and
are suggestive of a statistically significant difference. See text for further details.
25
-------
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.
15
-5
-15
-20
~20ng/L@ 17ft
-200 ng/L @ 91 fl
E~20|Jg/L@17ft
O-200 ua/L (a) 91 f<
11DCE 12DCA BNZ TCE 112TCA PCE
Compound
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.
26
-------
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
predemonstration 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.
27
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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.
28
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GCMS (Taz) Control Chart
TCE Check Standard
130
120
110
100
Upper Control Limit
S
in
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-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.
29
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GCMS (Taz) Control Chart
£ 110-
8
C£
ro
•a
1
o 90~
0)
.c
O
Upper Control Limit
m mmm mmm mmm mmm mmmm mmm mmm mmm Jmm mmm mmm mmm mm ••••••••
* •
+
•
A
i >
•
4
•
™ I
mm i
• *
» Start
• End
*
Lower Control Limit
8/9/99 8/10/99 8/11/99 8/12/99 8/13/99 8/14/99 8/15/99
Day
8/16/99 8/17/99
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 Check
50 ,
4Li
40
]>.h
e
1 JO
£
0
i -•*
t-f ""^
1
i*
"w
n
'0
5
n
|
IflrL n [L ferffl [I
ml1 ;lnl
r k\ • O •. .Si : rs •, -]
1 ^ ; | .i 1 : r
. J Nl U 1 :J l!
TS//S//S/A
BPcpc-TCE
DPepe-PCE
PTal-TCE
S Taz -PCE
I
»»««
;.;.;
I
N
!
Anafysis Date
Figure B-5. GC/MS system check relative percent differences.
30
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