agency washington, d.c. 20460 environmental technology ...report entitled environmental technology...

United States Office of Research and EPA/600/R-00/054Environmental Protection Development June 2000Agency Washington, D.C. 20460

Environmental TechnologyVerification Report

Groundwater SamplingTechnologies

Sibak Industries Ltd. Inc.

Kabis SamplerModels I and II

EPA/600/R-00/054June 2000

Environmental TechnologyVerification ReportGroundwater SamplingTechnologies

Sibak Industries Ltd. Inc.

Kabis SamplerModels I and II

by

Wayne EinfeldSandia National Laboratories

Albuquerque, New Mexico 87185

and

Eric N. KoglinU.S. Environmental Protection Agency

Environmental Sciences DivisionNational Exposure Research Laboratory

Las Vegas, Nevada 89193-3478

Notice

The U.S. Environmental Protection Agency (EPA), through its Office of Research and Development (ORD),funded and managed, through Interagency Agreement No. DW66940927 with Sandia National Laboratories,the verification effort described herein. This report has undergone peer and administrative review and hasbeen approved for publication as an EPA document. Mention of trade names or commercial products does notconstitute endorsement or recommendation for use of a specific product.

EPA-VS-SCM-39 The accompanying notice is an integral part of this verification statement. June 2000

ETV JOINT VERIFICATION STATEMENT

The U.S. Environmental Protection Agency (EPA) has created the Environmental TechnologyVerification Program (ETV) to facilitate the deployment of innovative or improved environmentaltechnologies through performance verification and dissemination of information. The goal of the ETVProgram is to further environmental protection by substantially accelerating the acceptance and use ofimproved 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 groupsconsisting of regulators, buyers, and vendor organizations, with the full participation of individualtechnology developers. The program evaluates the performance of innovative technologies bydeveloping 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 areconducted in accordance with rigorous quality assurance protocols to ensure that data of known andadequate quality are generated and that the results are defensible.

The Site Characterization and Monitoring Technologies Pilot, one of 12 technology areas under ETV, isadministered by EPA’s National Exposure Research Laboratory. Sandia National Laboratories, aDepartment of Energy laboratory, is one of the verification testing organizations within the ETV SiteCharacterization and Monitoring Pilot. Sandia collaborated with personnel from the US GeologicalSurvey to conduct a verification study of groundwater sampling technologies. This verificationstatement provides a summary of the results from a verification test of the Kabis Model I and IIdiscrete−level point samplers.

TECHNOLOGY TYPE: GROUNDWATER SAMPLING TECHNOLOGIES

APPLICATION: VOC-CONTAMINATED WATER SAMPLING

TECHNOLOGY NAME: Kabis Sampler, Models I and II

COMPANY: Sibak Industries Ltd. Inc.

ADDRESS: P.O. Box 86 PHONE: (800) 794-6244Solana Beach, CA 92075 (858) 793-6713

WEBSITE: www.sibak.com FAX: (619) 793-6713

EMAIL: [email protected]

THE ENVIRONMENTAL TECHNOLOGY VERIFICATIONPROGRAM


DEMONSTRATION DESCRIPTIONIn August 1999, the performance of six groundwater sampling devices was evaluated at the USGeological Survey (USGS) Hydrological Instrumentation Facility at the National Aeronautics and SpaceAdministration (NASA) Stennis Space Center in southwestern Mississippi. Each technology wasindependently evaluated in order to assess its performance in the collection of volatile organiccompound- (VOC) contaminated water.

The verification test design incorporated the use of a 5-inch-diameter,100-foot standpipe at the USGSfacility. The standpipe, serving as an “aboveground” well, was filled with water spiked with variousconcentration levels of six target volatile organic compounds. The target compounds (1,2-dichloroethane, 1,1-dichloroethene, trichloroethene (TCE), benzene, 1,1,2-trichloroethane, andtetrachloroethene) were chosen to represent the range of VOC volatility likely to be encountered innormal sampler use. Water sampling ports along the exterior of the standpipe were used to collectreference samples at the same time that groundwater sampling technologies collected samples from theinterior of the pipe. A total of seven trials were carried out at the standpipe. The trials included thecollection of low (~20 µg/L) and high (~200 µg/L) concentrations of the six target VOC compounds inwater at sampler depths ranging from 17 to 91 feet. A blank sampling trial and an optional “clean-through-dirty” trial were also included in the test matrix. The “clean-through-dirty” test was included toinvestigate the potential of contaminant carryover as a sampler is lowered through a "dirty" (high VOCconcentration) layer of water in order to sample an underlying "clean" (low VOC concentration) layer.

The standpipe trials were supplemented with sampler deployments at groundwater monitoring wells inthe vicinity of VOC-contaminated groundwater at the NASA Stennis facility. The Kabis samplingdevice was deployed in a number of 2-inch and 4-inch wells. Comparison samples were also collectedusing a submersible electric gear pump. The principal contaminant in the monitoring wells wastrichloroethene. The groundwater monitoring test phase provided an opportunity to observe theoperation of the sampling device under typical field-use conditions.

All technology and reference samples were analyzed by the same field-portable gas chromatograph-massspectrometer (GC/MS) system that was located at the test site during the verification tests. The GC/MSanalytical method used was a variation of EPA Method 8260 purge-and-trap GC/MS, with the use of aheadspace sampler in lieu of a purge-and-trap unit. The overall performance of the groundwatersampling technologies was assessed by comparison of technology and reference sample results withparticular attention given to key performance parameters such as sampler precision and accuracy.Aspects of field deployment and potential applications of the technology were also considered.

Details of the demonstration, including an evaluation of the sampler’s performance, may be found in thereport entitled Environmental Technology Verification Report: Sibak Industries Ltd. Inc., Kabis Sampler,EPA/600/R-00/054

TECHNOLOGY DESCRIPTIONThe Kabis Sampler is a discrete-level, grab sampler. The two models evaluated in this test operate on thesame principle and only differ in size and sampling capacity. Both samplers are constructed of 321stainless steel. The Model I is 17.4 inches long, 1.75 inches in diameter, and weighs 6.5 pounds. TheModel II is 22.3 inches long, 3.65 inches in diameter and weighs 15.5 pounds. Both samplers have aremovable top into which a single (Model I) or three (Model II) 40-mL VOA vial(s) are screwed prior tosampler deployment in the well. The sampler is attached to a measuring tape and is manually lowered intothe water column. The size and orientation of the inlet and exhaust ports of the sampler are such that itdoes not fill while it is being lowered down through the water column in the well. When the sampler isheld stationary at the desired sampling depth, it begins to fill under hydrostatic pressure. Fill duration timeis about 5 minutes for the Model I and 8 minutes for the Model II.


Air inside the sampler escapes through an exhaust port as the installed sample vials fill from the bottomupward. The vials are flushed with about 6 vial volumes prior to the collection of the final vial volumeat the end of the sampling cycle. The flush water flowing through the vials spills into the sampler bodythrough spill ports located in the vial holder in the sampler head. Following completion of the fill cycle,the sampler is manually retrieved to the surface and the sample vials removed. The sample is thenpreserved, if required, and the vials are capped with positive-displacement-type caps that ensure abubble-free sample. Sampler decontamination is carried out by rinsing the sampler in the field using a 5-gallon bucket of detergent water followed by several deionized or distilled water rinses.

Costs for the Kabis samplers are $825 for the Model I and $1,895 for the Model II. Additional sampleraccessories available include a delivery tape, wooden storage box, and positive-displacement VOA vialcaps.

The Model I and Model II samplers differ only in their size and number of vials filled during sampling.The samplers were used interchangeably in the study and their performance results are combined.Hereafter, the two sampler models are simply referred to as the Kabis sampler.

VERIFICATION OF PERFORMANCEThe following performance characteristics of the Kabis sampler were observed:

Precision: The precision of the sampler was determined through the collection of a series of replicatesamples from four standpipe trials using low (~20 µg/L) and high (~200 µg/L) VOC concentrations at17-foot and 91-foot collection depths. Each trial included 6 target VOCs for a total of 24 cases. Kabissampler precision, represented by the relative standard deviation, for all compounds at all concentrationsand sampling depths evaluated in this study, ranged from 2.9 to 25.8%, with a median value of 10.7%.Reference method precision ranged from 4.1 to 17.6%, with a median relative standard deviation valueof 8.7%. In 16 cases, the relative standard deviation of the Kabis samples was greater than the referencesamples, with Kabis precision less than or equal to reference sample precision in the other 8 cases. TheF-ratio test was used to assess whether the observed precision differences between Kabis and referencesamples were statistically significant. Test results showed that precision differences between Kabis andreference were statistically insignificant at the 95% confidence level in 23 of the 24 cases.

Comparability with a Reference: Kabis sampler results from the standpipe trials were compared withresults obtained from reference samples that were collected at the same time. Both Kabis and referencesamples were analyzed by the same analytical method using the same GC/MS system. Samplercomparability is expressed as percent difference relative to the reference data. Sampler differences forall target VOC compounds at all concentrations and sampler depths used in this study ranged from -39 to18%, with a median difference of -3%. The t-test for two sample means was used to assess whether theobserved differences in Kabis sampler and reference sample results were statistically significant. Thesetests revealed that in 16 of 24 trials, the differences were not statistically different at the 95% confidencelevel. Of the remaining 8 cases, 5 showed a statistically significant Kabis sampler negative bias; and in 2of those cases, the negative bias for PCE was in excess of 25%.

Versatility: Sampler versatility is the consistency with which the sampler performed over the ranges oftarget-compound volatility, concentration levels, and sampling depths. The standpipe tests revealgenerally consistent performance with regard to Kabis sampler precision. Kabis sampler results showlow recovery for TCE and PCE at the higher (~200 µg/L) concentration at the deeper (91 ft) samplinglocation used in this evaluation. In light of these results, the Kabis sampler is judged to have limitedversatility.

Logistical Requirements: The sampler can be deployed and operated in the field by one person. About1 hour of training is generally adequate to become proficient in the use of the system. The sampler is


compact and can easily be hand carried to the wellhead for use. Decontamination of the sampler can becarried out in the field by using a detergent water rinse followed by several distilled water rinses. Areasonable degree of manual dexterity is required to remove the sample vials from the sampler headwithout sample loss. Sampling vials that have been pre-preserved cannot be used in this sampler.Preservative must be added following sample collection, if required.

Overall Evaluation: The results of this verification test show that the Kabis sampler can be used tocollect VOC-contaminated water samples that are generally indistinguishable from a reference methodwith regard to precision. Sampler recovery, relative to reference samples, was acceptable for four of thesix target compounds. Test results indicated low sample recovery with the Kabis sampler for TCE andPCE at high concentrations at both shallow and deep sampling locations.

As with any technology selection, the user must determine if this technology is appropriate for theapplication and the project data quality objectives. For more information on this and other verifiedtechnologies, visit the ETV web site at http://www.epa.gov/etv.

Gary J. Foley, Ph.D. Samuel G. VarnadoDirector DirectorNational Exposure Research Laboratory Energy and Crit ical Infrastructure CenterOffice of Research and Development Sandia National Laboratories

NOTICE: EPA verifications are based on evaluations of technology performance under specific, predeterminedcriteria and appropriate quality assurance procedures. EPA and SNL make no expressed or implied warranties asto the performance of the technology and do not certify that a technology will always operate as verified. Theend 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.

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Table of Contents

List of Figures ................................................................................................................................................................................. iiiList of Tables.................................................................................................................................................................................... vAcknowledgments......................................................................................................................................................................... viiList of Abbreviations and Acronyms ...........................................................................................................................................ix

1 INTRODUCTION............................................................................................................................................................................1Background .......................................................................................................................................................................................1Demonstration Overview.................................................................................................................................................................1

2 TECHNOLOGY DESCRIPTION: KABIS SAMPLER...........................................................................................................3

3 DEMONSTRATION PROCESS AND DESIGN.......................................................................................................................5Introduction.......................................................................................................................................................................................5Site Description.................................................................................................................................................................................5Verification Test Design Summary ...............................................................................................................................................7Test Design Elements ......................................................................................................................................................................7Sampler Performance Parameters ..................................................................................................................................................9Sample Analysis .............................................................................................................................................................................10Data Processing ..............................................................................................................................................................................10Data Quality Control......................................................................................................................................................................10Verification Test Plan ....................................................................................................................................................................11Standpipe and GW Well-Sampling Matrix.................................................................................................................................11Chronological Summary of Demonstration Activities.............................................................................................................12Deviations from the Verification Plan ........................................................................................................................................13

4 PERFORMANCE EVALUATION FOR KABIS SAMPLER...............................................................................................15Introduction.....................................................................................................................................................................................15Sampler Precision...........................................................................................................................................................................15Comparability to Reference..........................................................................................................................................................15Blank and Clean-through-Dirty Performance............................................................................................................................18Monitoring Well Results ...............................................................................................................................................................18Sampler Versatility.........................................................................................................................................................................19Deployment Logistics ....................................................................................................................................................................19Performance Summary ..................................................................................................................................................................19

5 KABIS SAMPLER TECHNOLOGY UPDATE AND REPRESENTATIVE APPLICATIONS....................................21Vendor Observations on Clean-Through-Dirty Sampling.......................................................................................................21Example Field Applications .........................................................................................................................................................21

6 REFERENCES................................................................................................................................................................................23

APPENDICESA: REFERENCE PUMP PERFORMANCE...................................................................................................................................25B: QUALITY SUMMARY FOR ANALYTICAL METHOD....................................................................................................29

iii

List of Figures

1 Kabis sampler Model I (right) and Model II (left) .....................................................................................................................32 Illustration of the Kabis sampler filling sequence. .....................................................................................................................33 The standpipe at the USGS Hydrological Instrumentation Facility.........................................................................................64 Kabis sampler comparability with reference samples from the standpipe trials. ................................................................17A-1 Percent recoveries of the reference pump by compound for the four standpipe trials. ......................................................28B-1 Calibration check control chart for TCE on GC/MS#1............................................................................................................30B-2 Calibration check control chart for TCE on GC/MS#2............................................................................................................31B-3 Calibration check control chart for PCE on GC/MS#1............................................................................................................31B-4 Calibration check control chart for PCE on GC/MS#2............................................................................................................32B-5 GC/MS system check relative percent differences...................................................................................................................32

v

List of Tables

1 Construction Details of Groundwater Monitoring Wells ..........................................................................................................72 Target VOC compounds .................................................................................................................................................................73 Sampler Verification Trials at the Standpipe.............................................................................................................................124 Sampler Verification Trials at the Groundwater Monitoring Wells ......................................................................................135 Precision Summary for Kabis and Reference Sample..............................................................................................................166 Comparability of Kabis and Reference Sample Data from Standpipe Trials .......................................................................177 Clean-through-dirty Test Results for the Kabis Sampler.........................................................................................................188 Kabis Sampler and Reference Pump Results from Groundwater Monitoring Wells ..........................................................199 Performance Summary for Kabis Sampler.................................................................................................................................20A-1 Precision of Gear Pump and Reference Samples in Standpipe Trials...................................................................................26A-2 Comparability of the Gear Pump with the Reference Samples in Standpipe Trials ...........................................................27B-1 Onsite GC/MS-Headspace Method Quality Control Measures .............................................................................................29

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Acknowledgments

The authors acknowledge the support of all those who helped in the vendor solicitation, planning, fielddeployment and analysis phases of this verification test. In particular, we recognize Steve Gardner (US EPANERL, Las Vegas), who provided technical assistance and peer reviewed the test plan. We also acknowledgethe assistance of Eugene Hays, Bill Davies, and Ed Ford (US Geological Survey) in providing access to theStandpipe Facility at the NASA Stennis Space Center as well as for their technical assistance during thestandpipe 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 atthe NASA Stennis Space Center. Thanks also to Greg New (Foster Wheeler Environmental Corporation) forhis assistance in getting much of the site hydrological and well monitoring data into our hands during theplanning phases of this test. Finally, we thank Craig Crume and Mika Greenfield (Field Portable Analytical)for their care and diligence in sample analysis during the field trials.

For more information on the Groundwater Sampling Technology Verification Test, contact:

Eric Koglin Wayne EinfeldProject Technical Leader ETV Project ManagerEnvironmental Protection Agency Sandia National LaboratoriesEnvironmental Sciences Division MS-0755 PO Box 5800National Exposure Research Laboratory Albuquerque, NM 87185-0755P. O. Box 93478 (505) 845-8314 (v)Las Vegas, Nevada 89193-3478 E-mail: [email protected](702) 798-2432 (v)E-mail: [email protected]

For more information on the Kabis Samplers contact:

Thomas (Tom) W. KabisSibak Industries Limited Inc.P.O. Box 86Solana Beach, CA 92075800-794-6244 or (858) 793-6713 (v)e-mail: [email protected] [email protected]

ix

List of Abbreviations and Acronyms

BNZ BenzeneDIFF DifferenceEPA US Environmental Protection AgencyETV Environmental Technology Verification ProgramGC/MS Gas chromatograph-mass spectrometerHIF Hydrological Instrumentation FacilityMSL Mean sea levelMW Monitoring wellNASA National Aeronautics and Space AdministrationND Not detectedNERL National Exposure Research LaboratoryPCE Tetrachloroethene (perchloroethene)PTFE PolytetrafluoroethylenePVC Polyvinyl chlorideQA Quality assuranceQC Quality controlREF ReferenceRSD Relative standard deviationSCMT Site Characterization and Monitoring PilotSNL Sandia National LaboratoriesSP Sample portSSC Stennis Space CenterTCE TrichloroetheneUSGS US Geological SurveyVOA Volatile organics analysisVOC Volatile organic compound12DCA 1,2-dichloroethane11DCE 1,1-dichloroethene112TCA 1,1,2-trichloroethane

1

Section 1 — Introduction

BackgroundThe U.S. Environmental Protection Agency (EPA)has created the Environmental TechnologyVerification Program (ETV) to facilitate thedeployment of innovative or improvedenvironmental technologies through performanceverification and dissemination of information. Thegoal of the ETV Program is to furtherenvironmental protection by substantiallyaccelerating the acceptance and use of improvedand cost-effective technologies. ETV seeks toachieve this goal by providing high-quality, peer-reviewed data on technology performance to thoseinvolved in the design, distribution, financing,permitting, purchase, and use of environmentaltechnologies.

ETV works in partnership with recognizedstandards and testing organizations andstakeholder groups consisting of regulators,buyers, and vendor organizations, with the fullparticipation of individual technology developers.The program evaluates the performance ofinnovative technologies by developing test plansthat are responsive to the needs of stakeholders,conducting field or laboratory tests (asappropriate), collecting and analyzing data, andpreparing peer-reviewed reports. All evaluationsare conducted in accordance with rigorous qualityassurance (QA) protocols to ensure that data ofknown and adequate quality are generated and thatthe results are defensible.

ETV is a voluntary program that seeks to provideobjective performance information to all of theparticipants in the environmental marketplace andto assist them in making informed technologydecisions. ETV does not rank technologies orcompare their performance, label or listtechnologies as acceptable or unacceptable, seekto determine “best available technology,” orapprove or disapprove technologies. The programdoes not evaluate technologies at the bench orpilot scale and does not conduct or supportresearch.

The program now operates 12 pilots covering abroad range of environmental areas. ETV hasbegun with a 5-year pilot phase (1995–2000) totest a wide range of partner and procedural

alternatives in various pilot areas, as well as thetrue market demand for and response to such aprogram. In these pilots, EPA utilizes the expertiseof partner “verification organizations” to designefficient processes for conducting performancetests of innovative technologies. These expertpartners are both public and private organizations,including federal laboratories, states, industryconsortia, and private sector facilities. Verificationorganizations oversee and report verificationactivities based on testing and QA protocolsdeveloped with input from all majorstakeholder/customer groups associated with thetechnology area. The demonstration described inthis report was administered by the SiteCharacterization and Monitoring Technology(SCMT) Pilot. (To learn more about ETV, visitETV’s Web site at http://www.epa.gov/etv.)

The SCMT pilot is administered by EPA’sNational Exposure Research Laboratory (NERL).Sandia National Laboratories, one of twoverification organizations associated with theSCMT pilot, conducted a verification study ofgroundwater sampling technologies during thesummer of 1999. Groundwater samplingtechnologies are commonly employed atenvironmental sites for site screening andcharacterization, remediation assessment, androutine environmental monitoring. Groundwatersampling technologies generally fall into twocategories: (1) active systems, including pumpingsystems and discrete-level grab systems; and (2)passive or diffusional systems. Both types ofsamplers were evaluated during this verificationstudy.

Demonstration OverviewIn August 1999, a demonstration study wasconducted to verify the performance of sixgroundwater sampling systems: Multiprobe 100(Burge Environmental, Tempe, AZ), SamplEase(Clean Environment Equipment, Oakland, CA)Micro-Flo (Geolog Inc., Medina, NY), WellWizard (QED Environmental, Ann Arbor, MI),Kabis Sampler (Sibak Industries, Solana Beach,CA), GoreSorber (W. L. Gore and Associates,Elkton, MD), and the Kabis Sampler. This reportcontains an evaluation of the Kabis Sampler,

2

Models I and II, manufactured by Sibak IndustriesLtd., Solano Beach, CA.

It is important to point out that the scope of thistechnology demonstration was purposely limitedto sampling device performance parameters suchas precision, comparability to a referencemeasurement, and where applicable, deploymentlogistics. Several of the systems tested in thisstudy are intended for use with low-flow samplingprotocols—a relatively new approach to thecollection of a representative sample from agroundwater monitoring well. This study wasspecifically intended to evaluate sampling deviceperformance and did not evaluate the merits of alow-flow purge sampling protocol. This protocolhas been proposed, tested, and publishedelsewhere [Puls and Barcelona, 1996] and isbeyond the scope of this particular investigation.

The demonstration was conducted in August of1999 at the National Aeronautics and SpaceAdministration (NASA) Stennis Space Center(SSC) in southwestern Mississippi. Sandiaworked in cooperation with the US GeologicalSurvey (USGS), a federal agency resident at theNASA Stennis site, and used a 100-foot standpipetesting facility associated with the USGSHydrological Instrumentation Facility (HIF)located on the NASA site. The standpipe, servingas an “above-ground” well, was filled with waterspiked with various concentration levels of sixtarget volatile organic compounds (VOC). Watersampling ports along the exterior of the pipepermitted the collection of reference samples atthe same time that groundwater samplingtechnologies collected samples from the interior ofthe pipe.

The standpipe trials were supplemented withadditional trials at a number of groundwatermonitoring wells at sites with VOC-contaminatedgroundwater at the NASA Stennis facility. Thetechnologies were deployed in a number of 2-inchand 4-inch wells, along with the referencesamplers for comparison. The principalcontaminant at the site was trichloroethene.

All technology and reference samples wereanalyzed by the same field-portable gaschromatograph-mass spectrometer system that waslocated at the test site during the verification tests.The overall performance of the groundwatersampling technologies was assessed by comparingtechnology and reference sample results for anumber of volatile organic compounds, withparticular attention given to key parameters suchas sampler precision and comparability toreference sample results. Aspects of fielddeployment and potential applications of thetechnology were also considered.

A brief outline of this report is as follows: Section2 contains a brief description of the Kabis samplerand its capabilities. Section 3 outlines a shortdescription of the test facilities and a summary ofthe verification test design. Section 4 includes atechnical review of the data, with an emphasis onassessing overall sampler performance. Section 5presents a summary of the Kabis samplertechnology and provides examples of potentialapplications of the sampler in site characterizationand monitoring situations. Appendix A containsperformance data for the reference pump, andAppendix B presents an assessment of qualitycontrol data associated with the analytical methodused in this study.

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Section 2 — Technology Description: Kabis Sampler

This section provides a general description andoverview of the capabilities of the Kabis samplerModels I and II manufactured by Sibak Industries.The information used to prepare this section wasprovided by Sibak Industries.

Two Kabis samplers, the Model I and Model II, asshown in Figure 1, were evaluated in this test.They operate on the same principle and only differin size and sample capacity. The Model I is 17.4inch long with a 1.75-inch external diameter and aweight of 6.5 pounds. The Model II is 22.3 incheslong with a 3.55-inch external diameter and aweight of 15.5 pounds. Both samplers areconstructed of 321stainless steel and have aremovable top into which a single (Model I) orthree (Model II) 40-mL volatile organic analysis(VOA) vials are screwed prior to samplerdeployment in the well. The sampler is attached toa measuring tape and slowly lowered into the watercolumn. The orientation of the inlet and exhaustports of the sampler is such that the samplingchamber does not fill while it is being lowereddown through the water column. When the sampleris held stationary at the desired sampling depth, itbegins to fill by hydrostatic pressure. Fill time isabout 5 minutes for the Model I and 8 minutes forthe Model II.

Figure 1. Kabis sampler Model I (right) andModel II (left) .

The Kabis sampler employs simple physics for itsoperation. As illustrated in Figure 2, water surfacetension across the exhaust port (T1) is equal to thewater surface tension across the fill port (T2). Thehead pressure (h) imposed by the verticaldifference between the fill port (P1) and theexhaust port (P2) is only slightly greater than thesurface tension across both the fill and exhaustports. As the sampler is lowered past the air/waterinterface and down through the water column, thehydrostatic pressure (P) changes across both thefill and exhaust ports at a constant rate. As thehydrostatic head pressure increases, the imposedhead pressure (h) tends toward the asymptote ofzero. Since h approaches zero, the water surfacetension prevents water entry into either samplerport. As the sampler descent rate goes to zero atthe desired sampling depth, the imposed headpressure is restored and slowly overcomes thesurface tension at the fill port, and the fill cyclebegins.

Air inside the sampler escapes through the exhaustport and the installed sample vial(s) fills from thebottom of the vial upward. The vial(s) are flushedwith a total of about 6 vial volumes prior tocollection of the final vial volume. The flush

40-mL VOA vial

Outlet (air) port

Inlet (water) port

Figure 2. Illustration of the Kabis samplerfilling sequence.

4

water flowing through the vial spills into thesampler body through spill ports located in the vialholder on the sampler head. When the overflowwater in the sampler body reaches the bottom ofthe exhaust port, no more air can escape from thesampler body and the sampler fill cycle iscomplete. The sampler is then retrieved to thesurface. The sampling head is unscrewed from thebody of the sampler and the sample vials are thenremoved from the sample head. If samplepreservation is required, few drops of preservativesolution can be added. The vial is then cappedwith a positive-displacement-type cap that ensuresa bubble-free sample.

The Kabis sampler is designed to collect a samplefrom a well at a specific depth chosen by thesampler operator. It is a grab sampler and by virtueof this fact does not incorporate well purging in itsuse. Well purging, whether by a low-flow methodor traditional three-volume purge, may or may notbe required in monitoring applications. If site

sampling objectives require well purging, otherdevices could be used to carry out well purgingprior to the use of a Kabis unit for samplecollection.

The sampler has no moving parts and requires nomaintenance other than routine decontamination.Decontamination procedures consist of a detergentwater rinse followed by several distilled waterrinses and can be easily carried out in the field.

Costs for the two Kabis samplers are $825 for theModel I and $1,895 for the Model II. Sampleraccessories, not included in the base price, include adelivery tape, wooden storage box, and positive-displacement VOA vial caps.

Additional information on potential applications ofthe system for environmental characterization andmonitoring can be found in Section 5—TechnologyUpdates and Application.

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Section 3 — Demonstration Process and Design

IntroductionThe principal objective of this demonstration wasto conduct an independent evaluation of thecapabilities of several groundwater samplingtechnologies for VOC-contaminated water. Anumber of key performance parameters werechosen to evaluate overall sampler performance.In order to ensure data integrity and authenticity ofresults, data quality control measures were alsoincorporated into the study design. The designwas developed by personnel at Sandia NationalLaboratories with concurrence from the varioustechnology vendors participating in the study.Technical review of the study design was alsoprovided by EPA personnel with professionalexpertise in the area of groundwater sampling. Acomplete demonstration plan has been published[Sandia, 1999].

Site DescriptionThe John C. Stennis Space Center in southwestMississippi is one of ten NASA field centers in theUnited States. It is NASA's primary center fortesting and flight-certifying rocket propulsionsystems for the Space Shuttle and future generationsof space vehicles. Over the years, SSC has evolvedinto a multiagency, multidisciplinary center forfederal, state, academic, and private organizationsengaged in space, oceans, environmental programsand national defense. The HydrologicInstrumentation Facility supports USGSagencywide hydrologic data-collection activitiesthrough the identification of agency needs,development of technical specifications, andtesting and evaluation.

Standpipe Facility – One of the HIF test centers isknown as the Standpipe Facility. The facility wasdesigned by Doreen Tai, an HIF chemicalengineer, and is housed in a Saturn V rocketstorage building at the Stennis complex. Aschematic diagram of the standpipe andaccessories is shown in Figure 1. The standpipe isan aboveground, 100-foot-long, 5-inch-diameter,stainless steel pipe with numerous externalsampling ports along its length. Two large tanksat the top of the standpipe are used to preparesolutions that can then be drained into thestandpipe. The tanks are equipped with motor-driven mixing propellers and floating lids to

minimize loss of volatile compounds duringmixing and transfer of solution. An externalstandpipe fill line at the bottom of the pipe enablesthe pipe to be filled from the bottom up, therebyminimizing flow turbulence and VOC losses in theprepared solutions. The external access portsallow reference samples to be takensimultaneously with technology samples inside thepipe. As shown in Figure 1, the indoor facility hassix levels of access, including the ground floor,and all levels are serviced by a freight elevator. Inthis demonstration, the standpipe was used in aseries of controlled water sampling trials.Technology vendors sampled VOC-contaminatedwater solutions from the standpipe while referencesamples were simultaneously taken from theexternal ports.

Site Hydrogeology – The second phase of thistechnology demonstration involved the collectionof groundwater samples from six onsite wells atSSC. The site has about 200 wells that have beenused for subsurface plume characterization androutine groundwater monitoring. The shallow,near-surface geology where most of thecontaminant plumes are located can besummarized as follows [Foster Wheeler, 1998]:The geology generally consists of a thin veneer ofclayey sediments known as Upper Clay, and foundat elevations ranging from 10 to 30 feet mean sealevel (MSL), overlying a sandy unit named UpperSand (at 5 to 15 feet MSL) . The Upper Sand isunderlain by a second clayey unit named theLower Clay and a second sandy unit called theLower Sand (at –35 to 5 feet MSL). Below theLower Sand, another clayey unit is present whichrepresents an unnamed or undifferentiatedPleistocene deposit. This deposit is underlain by athick zone of interbedded sand and clay depositsthat form the Citronelle Formation (at –100 to –40feet MSL). The VOC contamination is present inthe Upper Sand and Lower Sand water bearingzones; correspondingly, most of the wells selectedfor use in this test were screened in these zones.

Groundwater Monitoring Wells – Constructioninformation for the six wells selected for use inthis study is given in Table 1. The wells wereconstructed with either 2-or 4-inch-diameterpolyvinyl chloride (PVC) pipe with a 10-foot PVC

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Figure 3. The standpipe at the USGS Hydrological Instrumentation Facility.

7

screen length. All samples were collected at themidscreen level. Typical sampling depths for thewells selected for study ranged from about 15 to85 feet from the top of the well column to thescreen midpoint. The depth of the water columnabove the midscreen point ranged from 5 to 68feet for the wells selected for use in this study.

Verification Test Design SummaryThe verification test design consisted of two basicelements. The first was a test matrix consisting ofseveral trials conducted under carefully controlledsampling conditions at the standpipe. These trialsenabled sampler performance parameters such asprecision and comparability with reference to beevaluated. The second element was an additionalseries of tests conducted under actual fieldconditions with inherently less experimentalcontrol. These trials presented an opportunity toobserve the technology in actual field use inconditions very similar to those that would beencountered in routine use. Together, these twostudy elements provided a data set that is adequatefor an overall performance assessment of thesegroundwater sampling devices for applicationsspecifically involving the sampling of VOC-contaminated groundwater.

Test Design ElementsThe test consisted of a variety of samplingactivities carried out under relatively closelycontrolled experimental conditions at thestandpipe, along with field sampling at selectedonsite monitoring wells under less controlledconditions. Additional design elementdescriptions are given below. The participatingtechnologies were split into two categories, activesamplers and passive samplers, with individualsampling trials designed specifically for these twocategories.

Target VOC Compounds—Six target compounds,all regulated under the EPA Clean Water Act,were selected for testing in this study. Thecompounds were 1,2-dichloroethane (12DCA),1,1-dichloroethene (11DCE), trichloroethene(TCE), benzene (BNZ), tetrachloroethene (PCE),and 1,1,2-trichloroethane (112TCA). With theexception of benzene, all of these compounds arechlorinated and have regulatory limits of 5 µg/L inwater as presented in the Clean Water Act. Thesix compounds selected encompass a range ofvolatility, a parameter that is likely to influencesampler performance. Target compound volatility,as represented by Henry's constants and boilingpoint information, is given in Table 2.

Table 1. Construction Details of Groundwater Monitoring Wells

Screen Elev.(ft, MSL)

WellNo.

TOC(ft, MSL)

TotalDepth

(ft) Top Bottom

WellDia.(in.)

InstallDate

Depthto

Water(ft)

WaterLevel

(ft,MSL)

Water DepthAboveScreen

Midpoint (ft)06-04 28.8 39.0 -1.3 -11.3 2 04/95 24.6 4.2 10.506-10 7.8 87.0 -55.2 -65.2 4 04/95 8.2 -0.4 59.806-11 15.3 150.0 -62.8 -72.8 4 05/95 15.2 0.1 67.906-20 7.3 75.0 -55.4 -65.4 4 12/96 7.8 -0.6 59.812-09 28.0 18.0 18.0 8.0 2 05/95 10.0 18.0 5.012-12 28.4 99.0 -11.0 -21.0 4 05/95 11.6 16.8 32.8

Notes: TOC = top of well column; water levels from most recent quarterly well monitoring data.

Table 2. Target VOC compounds

Compound Henry’s Constant(kg•bar/mole at 298 K)a

Boiling Pt.(ºC)

Tetrachloroethene (PCE) High (17.2) 1211,1-Dichloroethene (11DCE) High (29.4) 32Trichloroethene (TCE) Mid (10.0) 87Benzene (BNZ) Mid (6.25) 801,2-Dichloroethane (12DCA) Low (1.39) 841,1,2-Trichloroethane(112TCA)

Low (0.91) 114

a Henry's constant data from NIST, 2000.

8

Test Concentrations—The use of the standpipefacility enabled the preparation of water mixturescontaining the six target VOCs in a range ofconcentration levels. In four standpipe testingtrials, the target compound concentration waseither low (10-20 µg/L) or high (175-225 µg/L).Spike solutions of all six target compounds wereprepared in methanol from neat compounds. A5-10 mL volume of the spiking solution wasinjected into the mixing tank, which was located atthe top of the standpipe and contained about 100gallons of tap water. This solution was coveredwith a floating lid to reduce volatile losses, gentlymixed for 5 minutes, and then drained into thestandpipe.

Standpipe Reference Sample—Preliminary studiesat the standpipe revealed volatile losses of targetcompounds during mixing and filling.Consequently, calculated spike concentrationscould not be used as a reference values in thisstudy. The standpipe had external sampling portsalong its length so that reference samples could becollected simultaneously with the samples fromthe interior of the pipe with devices undergoingtesting. Each sampling trial consisted of thesimultaneous collection of replicate test device andreference samples at a fixed concentration andsampling depth. The reference samples werecollected directly into analysis vials with nointervening pumps or filters that could affect thesample. The use of multiple sequentially collectedsamples allowed the determination of test deviceand reference sample precision. Precision in thiscontext incorporates the variability of thetechnology and the reference sample incombination with the common analytical methodused on both sample types. The reference sampleprecision is assumed to be the baseline with whichthe technology precision data can be directlycompared for each of the sampling trials.

Sampler Blank—The standpipe trials included ablank test in which replicate samples werecollected from a blank water mixture in thestandpipe. This test was conducted to assesswhether the construction materials in the varioussamplers could be a source of contamination of thesample for the six target compounds used in thisstudy.

Sampler Carryover—One of the intendedapplications of several of the samplers involved in

the study is the collection of a water sample withrelatively low VOC levels at a discrete level in awell that may have overlying layers of VOCcontamination at higher levels. A so-called clean-through-dirty test was incorporated to assess thedegree to which the samplers were contaminatedin the high-level layer that was penetrated as thesampler was lowered to a cleaner underlying layerin the well. The results of these trials are alsoexpressed in terms of percent difference fromreference samples, with recovery valuessignificantly greater than zero indicating samplercontamination from the overlying contaminatedlayers in the well.

Groundwater Well Reference Samples—Six onsitegroundwater monitoring wells were selected foruse in the second phase of the study. Asubmersible electric gear pump (Fultz, Model SP-300) was chosen as a reference sampling devicefor these additional field tests. Verification studieson the performance of this pump were carried outduring the standpipe phase of the experiments toprovide technical data substantiating its use as areference method in the field. A more completedescription of the pump along with a summary ofthese data is given in Appendix A. During fieldsampling events, the reference pump was co-located in the well with the sampling devices inorder to provide simultaneous reference samplesfrom the well. Teflon tubing (¼-inch outsidediameter) was used to transport the water samplefrom the pump outlet to the collection vial at thewellhead. During all sampling, the pump wasoperated at a low flow rate (100-200 mL/min).During Kabis sampler testing in groundwatermonitoring wells, the reference pump and theKabis sampler could not be simultaneouslydeployed in the well as a result of spacelimitations. In these instances, the Kabis samplerwas deployed first and replicate samples werecollected. Following Kabis sample collection, thereference pump was immediately deployed and asecond set of reference samples was collected.

As noted previously, the field sampling trials werenot an evaluation of the low-flow purgemethodology for well sampling. Consequently,water quality parameters were not monitored inthe field sampling trials. The presampling purgewas used to flush the reference pump and tubing toensure that the pump was drawing from the wellcolumn water. Whether formation water was

9

being sampled was of secondary importance inthis sampling plan.

Sampler Performance ParametersFour performance parameters were evaluated inthe assessment of each technology. They arebriefly outlined in the following paragraphs.

Precision—Sampler precision was computed forthe range of sampling conditions included in thetest matrix by the incorporation of replicatesamples from both the standpipe and thegroundwater monitoring wells in the study design.The relative standard deviation (RSD) was usedas the parameter to estimate precision. The percentrelative standard deviation is defined as the samplestandard deviation divided by the sample meantimes 100, as shown below:

2( - )1(%) 100

X XinRSDX

∑−= •

Here, Xi is one observation in a set of n replicatesamples where X is the average of allobservations, and n is the number of observationsin the replicate set. In the assessment of samplerprecision, a statistical test was used to assesswhether differences between the reference sampleprecision and the technology sample precisionwere statistically significant. Specifically, the F-ratio test was used to compare the variance (squareof the standard deviation) of the two groups toprovide a quantitative assessment as to whetherthe observed differences between the twovariances are the result of random variability orthe result of a significant influential factor in eitherthe reference or technology sample groups[Havlicek and Crain, 1988a].

Comparability—The inclusion of referencesamples, collected simultaneously with technologysamples from the external sampling port of thestandpipe, allows the computation of acomparability-to-reference parameter. The termcomparability is to be distinguished from the termaccuracy. Earlier investigations at the standpiperevealed that volatility losses occurred when thespike mixtures were mixed and transported duringstandpipe filling. As a result, the "true"concentrations of target VOCs in the standpipewere not precisely known and thus an accuracy

determination is not warranted. Alternatively, areference measurement from the external port,with its own sources of random error, is used forcomparison. The term percent difference is usedto represent sampler comparability for each of thetarget compounds in the sampling trials at thestandpipe. Percent difference is defined asfollows:

( )tech ref

ref

%DIFF 100X X

X

−= •

where is techX the average reported concentration

of all technology sample replicates and refX is theaverage reported concentration of all referencesample replicates. The t-test for two samplemeans was used to assess differences between thereference and technology means for each samplingtrial [Havlicek and Crain, 1988b]. The t-test givesthe confidence level associated with theassumption that the observed differences are theresult of random effects among a single populationonly and that there is no significant bias betweenthe technology and reference methods.

Versatility—The versatility of the sampler wasevaluated by summarizing its performance overthe volatility and concentration range of the targetcompounds as well as the range of samplingdepths encountered in both the standpipe and thegroundwater monitoring well trials. A samplerthat is judged to be versatile operates withacceptable precision and comparability withreference samples over the range of experimentalconditions included in this study. Those samplersjudged to have low versatility may not performwith acceptable precision or comparability forsome of the compounds or at some of the testedsampling depths.

Field Deployment Logistics—This final categoryrefers to the logistical requirements fordeployment of the sampler under its intendedscope of application. This is a more subjectivecategory that incorporates field observations madeduring sampler deployment at the groundwatermonitoring wells. Logistical considerationsinclude such items as personnel qualifications andtraining, ancillary equipment requirements, andfield portability.

10

Operator Influence—The sampling technician aswell as the sample collection method have aninfluence on the overall quality of the samplestaken. This is particularly true for the activesamplers evaluated in this study. Such factors asthe sample flow rate when filling the vial with abladder pump, the cycle times and volume ofbladder pump and others may influence overallsample quality. An evaluation of operatorinfluence on sample quality is beyond the scope ofthis study. All operators were experienced in theuse of their technologies and the assumption ismade that these operators were operating theirsampling devices under conditions that wouldyield the highest quality samples.

Sample AnalysisA single analytical method was used fortechnology and reference samples. All analyseswere conducted onsite, using analytical servicesprovided by Field Portable Analytical (Fremont,CA). The onsite instrumentation consisted of twoidentical field-portable gas chromatograph-massspectrometer (GC/MS) units (Inficon, HAPSITE,Syracuse, NY) equipped with an Inficonheadspace sampling system. The analysis methodused was a modified Method 8260 (purge-and-trapGC/MS) with headspace sampling replacing thepurge-and-trap portion of the method [EPA, 1996].Throughput was on the order of 4 to 6 samples perhour per instrument for a daily throughput of60-70 samples per instrument. The Inficon field-portable GC/MS system with headspace vaporsampling accessory had previously gone throughthe ETV verification process. Results from thisverification study showed that system accuracyand precision for VOCs in water analysis werecomparable with a conventional fixed laboratoryanalysis using purge-and-trap sample handlingcombined with bench-top GC/MS analyticalsystems [EPA, 1998].

A brief summary of the analytical method follows:Samples were brought to the analysis location in40-mL VOA vials and kept at temperatures near 4ºC until they were prepared for instrumentanalysis. As a result of the relatively high samplethroughput and the use of two instruments, sampleholding times did not exceed 24 hours in mostcases. Consequently, no sample preservativeswere used in the study. Immediately prior toanalysis, the chilled VOA sample vials wereuncapped and immediately transferred to a 50-mLglass syringe. Half (20 mL) of the sample was

then transferred to a second 40-mL VOA vial andthe vial was immediately capped. A 5-µL solutioncontaining internal standards and surrogatestandards was injected through the septum cap ofthe vial. The vial was then placed in theheadspace sampling accessory and held at 60 ºCfor 15 minutes. The original vial was again filledwith the remainder of the sample, capped, and heldunder refrigeration as a spare. Following thetemperature equilibration time, a vapor extractionneedle was inserted through the vial’s septa capand into the headspace. A pump in the GC/MSthen sampled a fixed volume of headspace gasthrough a heated gas transfer line and in a fixed-volume gas sampling loop in the GC/MS. Underinstrument control, the gas sample was theninjected onto the capillary column for separationand subsequent detection. An integrated datasystem processed the mass detector data andoutput results for the six target analytes plusinternal and surrogate standards in concentrationformat. The method used the internal standardmethod (as outlined in Method 8260) forcomputation of target compound concentrations.Surrogate standard results were used as measuresof instrument data quality, along with other qualitycontrol measures outlined below.

Data ProcessingThe results from chemical analysis of bothtechnology and reference samples were compiledinto spreadsheets and the arithmetic mean andpercent relative standard deviation (as defined inSection 3) were computed for each set of replicatesamples from each standpipe and monitoring welltrial. All data were reported in units ofmicrograms per liter for the six target compoundsselected. Direct trial-by-trial comparisons werethen made between technology and referencesample results as outlined below. All theprocessed data from the verification study hasbeen compiled into data notebooks and areavailable from the authors by request.

Data Quality ControlThe desirability of credible data in ETVverification tests requires that a number of dataquality measures be incorporated into the studydesign. Additional details on data quality controlare provided in the following paragraphs.

Sample ManagementAll sampling activitieswere documented by Sandia National Laboratories(SNL) field technicians using chain-of-custody

11

forms. To save sample handling time andminimize sample labeling errors in the field,redundant portions of the chain-of-custody formsand all sampling labels were preprinted prior to thefield demonstration.

Field LogbooksField notes were taken byobservers during the standpipe and groundwaterwell-sampling trials. The notes include a writtenchronology of sampling events, as well as writtenobservations of the performance characteristics ofthe various technologies tested during thedemonstration.

Predemonstration Analytical System AuditPriorto the actual demonstration, a number of samplescontaining the six target compounds at variousconcentration levels were prepared at SNL andsent via overnight Express Mail in an ice pack toField Portable Analytical near Sacremento, CA.They were analyzed by GC/MS analysis using theheadspace method intended for use in the finalfield test. Results from this preliminary auditrevealed acceptable performance of the GC/MSsystem and its accompanying method. The writtenanalytical method that was used during the fulldemonstration was also reviewed and finalized atthis time.

Analytical MethodThe analytical method was anadaptation of EPA Method 8260B and followedthe data quality requirements outlined in themethod. Included in the list of data qualitymeasures were: (1) initial calibration criteria interms of instrument linearity and compoundrecovery, (2) daily instrument calibration checks atthe onset and completion of each 12-hour analysisshift, (3) blank sample instrument performancechecks, (4) internal standard recovery criteria, and(5) surrogate standard recovery criteria. Asummary of the GC/MS analysis quality controldata for the demonstration period is given inAppendix B.

Verification Test PlanThe preceding information, as well as that whichfollows, is summarized from the GroundwaterSampling Technologies Verification Test Plan[Sandia, 1999], which was prepared by SNL andaccepted by all vendor participants prior to thefield demonstration. The test plan includes a morelengthy description of the site, the role andresponsibilities of the test participants, and adiscussion of the experimental design and dataanalysis procedures.

Standpipe and GW Well-SamplingMatrixThe sampling matrix for the standpipe samplingphase of the demonstration is given in Table 3.All standpipe and groundwater well testing wascarried out sequentially, with the variousparticipants deploying their technologies one at atime in either the standpipe or the groundwatermonitoring wells. A randomized testing order wasused for each trial. The standpipe test phaseincluded seven trials. Trials 1 and 2 were carriedout at shallow and deep locations with the a lowconcentration (10-20 µg/L) standpipe mixture.Trials 3 and 4 were conducted at shallow and deeplocations with a high-concentration (175-225µg/L) standpipe mixture. In all trials, referencesamples were collected from external samplingports simultaneously with sample collection by thedevice under test.

Trial 5 was a blank mixture measurement at thestandpipe to test the cleanliness of each sampler.For this trial, the standpipe was filled with tapwater and three replicates were collected by thedevice under test from the deep location in thepipe while three reference replicates werecollected simultaneously from the adjacentexterior sampling port.

Trials 6 and 7 at the standpipe were termed “clean-through-dirty” tests and were designed to evaluatethe discrete-level sampling performance of theKabis sampler. This test was optional for the other

12

Table 3. Sampler Verification Trials at the Standpipe

Trial No. StandpipeCollection

Port

SampleCollectionDepth (ft)

VOC ConcentrationLevel

No. of Replicatesper

Technology1 SP14 Low (17) Low (~20 µg/L) 5

2 SP3 High (92) Low (~20 µg/L) 5

3 SP14 Low (17) High (~200 µg/L) 5

4 SP3 High (92) High (~200 µg/L) 5

5 SP3 High (92) Blank 36 SP3 High (92) Mixed (high over low) 47 SP12 Low (35) Mixed (high over low) 4

Notes: In each trial, an equal number of reference samples were collected simultaneously with the technology samplesfrom adjacent external standpipe sampling ports. Sample collection points during trials 6 and 7 were from the low VOCconcentration region after the sampler was lowered through a high VOC concentration region.

active samplers. Those sampling systems thatwere intended for permanent deployment in a wellwere not required to participate in the “clean-through-dirty” sampling trials, although somechose to participate voluntarily. In this test, twomixtures, a high (~200 µg/L) and a low (~20µg/L), were prepared in the mixing tanks. Thepipe was then filled so that the high-level mixtureoccupied 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 andapproximate midpoint of the pipe after beinglowered through the high-level mixture at the topof the pipe. Reference samples weresimultaneously collected from the externalsampling ports in the same manner as for theprevious standpipe trials.

The onsite groundwater sampling matrix is shownin Table 4. Two of the wells originally scheduledfor use were dropped from the sampling matrixbecause the TCE concentrations were below theinstrument detection limit. The groundwatersampling procedure for the Kabis and referencesampler was as follows: As a result of the limitedspace available in the 2- and 4-inch diameterwells, the Kabis sampler and reference pumpcould not be deployed in the well at the same time.A modified sampling protocol was used in whichthe Kabis sampler was first delivered to themidscreen depth and four replicate samples werecollected. In most cases, a single delivery of theKabis sampler to the well was used and any VOAvials in addition to those installed on the samplerhead were filled from the overflow reservoir of theKabis sampler. Following Kabis sampler retrieval,

the reference pump was installed at the samemidscreen level in the well. A purge volume ofabout 1 to 2 liters was drawn through the referencepump at a flow rate between 100 to 200mL/minute. Following this purge, four replicatesamples were collected.

Chronological Summary ofDemonstration ActivitiesThe demonstration began on Monday, August 9and concluded on Tuesday, August 17. The firstfour days of the demonstration were devoted totesting those technologies designated “activesamplers.” Included in this group were BurgeEnvironmental (multilevel sampler), CleanEnvironment Equipment (bladder pump), Geolog(bladder pump), QED Environmental (bladderpump), and Sibak Industries (discrete-level grabsampler). The second half of the demonstrationwas devoted to testing the “passive sampler”category, of which W. L. Gore (sorbent sampler)was the only participant. A short briefing washeld on Monday morning for all vendorparticipants to familiarize them with the standpipefacility and the adjacent groundwater monitoringwells. Standpipe testing began for the activesampler category at midmorning on Monday andwas completed on the following day. Two days oftesting at the groundwater wells followed. Thepassive sampler category tests were begun at thestandpipe Thursday, August 12 and werecompleted on Monday, August 16. The passivesampler category was also deployed at a numberof monitoring well sites simultaneously withstandpipe testing.

13

Table 4. Sampler Verification Trials at the Groundwater Monitoring Wells

Trial Well Distance fromTop of Well toScreen Mid-

point (ft)

Water ColumnDepth

(ft)

ApproximateTCE Conc.

(µg/L)

No. ofReplicates per

Technology

10 06-20MW 67.7 59.9 <5 411 06-11MW 83.1 69.0 500 413 06-04MW 35.1 9.8 500 414 12-09MW 15.0 5.2 20 4

Notes: Reference samples were collected using a submersible electric sampling pump that was colocated with the Kabissampler in 4-inch wells and after the Kabis sampler in 2-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. Sampling methodologyconsisted of a three-well volume purge followed by sample collection with a bailer.Trials 12 and 15 were no-detect wells and were dropped from the data set.

Sample analysis was performed in a mobilelaboratory parked near the standpipe and wascarried out concurrently with field testing. Withthe exception of the first day of sample analysis,all technology and matched-reference sampleswere analyzed on the same instrument and usuallyon the same day. This approach was taken tominimize the possible influence of instrumentvariability on the analysis results.

The demonstration technical team observed andrecorded the operation of each technology duringboth standpipe and monitoring well trials to assistin the assessment of logistical requirements andease of use of the technology. These observationsalso were used to document any performanceanomalies as well as the technical skills requiredfor operation.

Deviations from the VerificationPlanUnder most field testing environments,circumstances often arise that prevent a completeexecution of the test plan. A list of the deviationsfrom the test plan that are judged to be importantare summarized below and an assessment of theresulting impact on the field test data set isincluded.

Lost/Dropped SamplesOut of over 800 samples,1 was dropped and lost in the field and 3 were notanalyzed either because they were overlooked orlost in handling by the field technicians oranalysts. Because 4 or 5 replicates were collectedin each sampling trial, the loss of a few samples

does not affect the overall study results. No Kabisor Kabis reference samples were lost during thetesting.

QC-Flagged DataSeveral samples on the firstday of GC/MS operation were reported with lowinternal standard recovery as a result of gastransfer line problems. A close examination of thedata revealed that these results are comparablewith replicate sample results that passed QCcriteria. Consequently, these data were used in thefinal analysis. A note indicating the use of flaggeddata is included in the appropriate data tables. Noflagged data were encountered with regard toKabis and associated reference samples in thisstudy.

Samples Below Quantitation Limit ofGC/MSOne of the wells sampled producedreference and vendor samples that were at orbelow the practical quantitation limit of theGC/MS system. These data were manually re-processed by the analyst to provide aconcentration estimate. Where this occurs, thesedata are flagged and appropriate notice is given inthe analysis section of this report.

Blank GW Monitoring WellsSix groundwatermonitoring wells were selected for study, based onpreliminary assessment of observed TCEconcentration levels using either historical data ordata from previous onsite well screening activities.In three trials, well TCE concentration levels werebelow the limits of detection, despite evidence tothe contrary from preliminary screening. Samplertubing carryover contamination was determined to

14

be the cause of the erroneous screening data. Oneof the “blank” wells was kept in the data set toassess sampler blank performance in the field.The other wells were dropped from the list oftrials. The impact on the overall data set is notimportant, since most of the objective parametersof performance, such as sampler accuracy andprecision, are derived from the standpipe data.

Questionable Sampling Procedure—In severalsampling events at both the standpipe andmonitoring wells, the Kabis sampler operatorfilled some of the replicate sample vials bypouring from the sampler sump instead ofdeploying the sampler a second time into thestandpipe or well. This procedure may haveinfluenced the analysis results; however, since theprocedure was done infrequently, the effects onsample quality cannot be ascertained in this study.

Filling sample vials from the sump is not arecommended practice in normal sampler use.

Unverified Performance Claim—One of theperformance claims associated with the Kabissampler is that no well purging is required in orderto acquire a sample that is representative offormation water. Performance claims of thevarious vendor participants in the study associatedwith the merits of low volume purging or nopurging were beyond the scope of this study andwere not evaluated. Furthermore, the design andoperation of the Kabis sampler is such that areference sampler could not be co-located in themonitoring wells for comparative purposes. Thus,quantitative comparisons of Kabis and referencesamples from the groundwater monitoring wellswere not possible in this study.

15

Section 4 — Performance Evaluation for Kabis Sampler

IntroductionThis section briefly discusses the results of testdata analysis and summarizes samplerperformance. Sampler precision, comparabilitywith reference sample data, and overall versatilityof the sampler for collection of VOC-contaminated water are discussed. Only summarydata are given in this report. A completetabulation of all test data are available from theauthors via individual request. The Kabis Model Iand Model II samplers were used interchangeablyin these tests. They are identical in design andmethod of operation and only differ by size ofsample collected. All data are combined andreported under the term “Kabis sampler.”

Sampler PrecisionThe precision for both Kabis and referencesamples from the first four standpipe trials is givenin Table 5. The first four trials consisted of low(10-20 µg/L) and high (175-225 µg/L) targetcompound concentrations, with sample collectionat shallow (17 feet) and deep (91 feet) locations inthe standpipe, as outlined previously in Table 3.Relative standard deviations are tabulated bycompound with 4 test conditions (lowconcentration at shallow sampling depth, highconcentration at shallow sampling depth, and soon) shown for each compound, for a total of 24cases. The final column in the table is the result ofthe F-ratio test used to assess whether thetechnology and reference precision values arestatistically different. The value p tabulated in thefinal column of the table is a measure of theobserved difference between the two values inprobabilistic terms. Values of p that are close to 1indicate small differences between the twoprecision values, and low values of p indicategreater differences. Values of p that are less than0.05 are indicative of statistically significantdifferences that cannot be satisfactorily explainedby random variation alone in the two sets of databeing compared. If the assumption is made thatthe two data sets being compared are from thesame population, and only random effects areoccurring, the probability of observing adifference in two precision values correspondingto a 0.05 value of p is 5%. In other words, such anobserved difference would be highly unlikely. For

values of p less than 0.05, it is more likely thatsome systematic bias exists between the two setsof data.

The results shown in Table 5 can be summarizedas follows. Relative standard deviations from lowand high sample concentrations do notsignificantly vary for both Kabis and referencedata. The greatest imprecision in the Kabis andreference results are encountered for 112TCA inthe deep collection, low concentration test.Preliminary evaluations of GC/MS performancecarried out prior to the field demonstrationrevealed that this compound had higher analyticaluncertainty than the other target compounds, sothe observed effect can be attributed to theanalytical method and not the sampling process.The median RSD for all compounds and all trialswas 10.7% for the Kabis sampler and 8.7% for thereference samples. Sixteen of the Kabis samplerprecision values were less precise than thereference values, and 8 were more precise than thereference values. The results of the F-ratio testindicate that only 1 of the 24 cases had a value ofp that was less than 0.05. Thus, differences inprecision between Kabis and reference samples arestatistically insignificant in 23 of the 24 cases.

Comparability to ReferenceThe comparability of the Kabis sampler data withreference data for standpipe trials 1 through 4 isgiven in Figure 4 and Table 6 and are expressed aspercent differences. Percent difference valueswere computed for each of the six targetcompounds in the four standpipe trials for a totalof 24 cases. The difference values for the Kabissampler range from −39 to 18%, with a medianvalue of −3%. By compound, the greatestvariability in results is seen for 12DCA, PCE andTCE and the lowest for benzene and 112TCA.Percent difference values for 14 of the 24 resultsshown in Table 6 were less than zero with another10 values above zero, thus no consistent bias ineither direction is observed when all cases aregrouped together. A t-test for two sample meanswas performed to assess whether the differencesbetween the Kabis sampler and reference meanvalues could be attributed to random variation orto a systematic bias for each case. As notedpreviously in the discussion on precision, values of

16

p that are less than 0.05 are suggestive of asystematic bias between the Kabis and referencesample results. Most of the results (16 of 24) showno statistically significant difference betweenKabis and reference results. T-test results for 8 ofthe 24 cases have values of p less than 0.05. Fiveof those 8 cases show a Kabis sampler negativebias ranging from −14 to −39% and these all occurat the high VOC concentration levels. Negativebias is judged to be of most importance since onlyVOC losses are expected during the sampling

process. Negative biases in excess of 25% wereobserved for 2 PCE cases at high VOCconcentrations at both shallow and deep samplecollection points. If one were to use a negativesampler bias performance criteria of 25% orgreater as unacceptable performance, these resultsshow that the sampler would perform acceptablyfor all compounds tested except PCE. Actualperformance criteria for a particular applicationmay vary and should be established by the siteinvestigator on a case-by-case basis.

Table 5. Precision Summary for Kabis and Reference Sample

Compound Conc.Level

SamplingDepth

(ft)

KabisPrecision(% RSD)

REFPrecision(% RSD)

F-Ratio F-RatioTest

p11DCE Low 17 14.1 7.2 3.58 0.24

Low 91 7.3 11.7 2.32 0.44High 17 11.4 7.9 2.14 0.48High 91 11.3 9.3 1.08 0.94

12DCA Low 17 5.6 5.5 1.34 0.78Low 91 2.9 9.6 8.79 0.06High 17 8.9 4.6 5.15 0.14High 91 5.3 10.9 4.34 0.18

BNZ Low 17 5.8 7.6 1.62 0.65Low 91 6.8 7.0 1.04 0.97High 17 10.7 4.1 7.36 0.08High 91 8.0 9.2 1.68 0.63

TCE Low 17 6.0 15.3 7.47 0.08Low 91 18.0 12.0 2.30 0.44High 17 10.6 8.7 1.11 0.92High 91 11.4 9.4 1.16 0.89

112TCA Low 17 15.4 12.1 1.35 0.78Low 91 25.8 17.6 2.04 0.51High 17 7.5 6.1 1.73 0.61High 91 5.7 8.6 1.06 0.39

PCE Low 17 11.0 4.6 4.78 0.16Low 91 19.7 4.9 15.52 0.02High 17 13.3 11.2 1.28 0.81High 91 12.6 7.5 7.5 0.96

Notes: Values of p less than 0.05 are shown in bold. REF = reference measurement

17

Figure 4. Kabis sampler comparability with referencesamples from the standpipe trials.

Table 6. Comparability of Kabis and Reference Sample Data from Standpipe Trials

Compound Conc. Levela Depth (ft) Kabis Difference (%) t-Testb p11DCE Low 17 -4 0.60

Low 91 6 0.37High 17 1 0.84High 91 -14 0.04

12DCA Low 17 14 <0.01Low 91 11 0.04High 17 18 <0.01High 91 -2 0.75

BNZ Low 17 3 0.58Low 91 5 0.30High 17 5 0.41High 91 -11 0.07

TCE Low 17 -6 0.42Low 91 1 0.92High 17 -14 0.04High 91 -24 <0.01

112TCA Low 17 -9 0.31Low 91 -2 0.87High 17 7 0.18High 91 -5 0.26

PCE Low 17 -9 0.10Low 91 -3 0.76High 17 -26 <0.01High 91 -39 <0.01

a The low-level concentration was in the range of 10 to 20 µg/L for all 6 target compounds. The high-levelconcentration was in the range of 175 to 225 µg/L.b The t-test was used to compare the differences between the Kabis and the reference results for each compound in eachtrial. The value p yields a quantitative estimate in probabilistic terms of the likelihood of the difference beingattributable to random variation alone. See text for further details.

18

Blank and Clean-through-DirtyPerformanceThe results from standpipe trials using blanksolutions show that the Kabis sampler reportednondetectable levels for all six target compounds.These results indicate that a Kabis sampler, whendecontaminated using the procedures specified inSection 2, will not contaminate a sample withchemical carryover from previous use.

The results of the clean-through-dirty test at thestandpipe are shown in Table 7. The sampler waslowered through a layer of relatively high (~200µg/L) target VOC concentrations at the top of thestandpipe for sample collection at a depth of 35and 91 feet in water with lower (approximately 15to 50 µg/L) VOC concentrations. The tabulatedresults are shown in terms of percent differencerelative to the reference samples collectedsimultaneously with the Kabis samples. Note thatthe tabulated difference levels for this trial are rawvalues in the sense that they are not normalizedwith the percent difference levels shown in Table6. Difference levels for the Kabis sampler for allcompounds at both depths vary from 38 to 187%,giving evidence that the sampler is eitherentraining contaminants from the dirty layer or it

is collecting a partial sample as it is loweredthrough the dirty layer. This carryover may be ofconcern when the sampler is deployed at amultiscreened well with high levels ofcontaminants overlying lower contaminant levelsat the desired sampling depth.

Monitoring Well ResultsKabis sampler results from groundwatermonitoring samples collected at four wells areshown in Table 8 alongside reference data fromthe same wells. Four replicate samples were takenwith the Kabis sampler and the reference sampler(a submersible electric gear pump), and relativestandard deviation values are also given in thetable. A few general observations from these dataare warranted: First, the field trials were carriedout primarily to provide an opportunity to observethe deployment and operation of the technologyunder actual field conditions. Second, formalstatistical analyses of these data have not beencarried out since the standpipe trial data set isjudged to be a superior data set for thedetermination of precision and comparability to areference measurement. The data are shown forqualitative comparison with the standpipe results,and significant differences are noted whereappropriate.

Table 7. Clean-through-dirty Test Results for the Kabis Sampler

Com-pound

SamplingDepth

(ft)

KabisAverage

Concentration(µg/L)

KabisPrecision(%RSD)

ReferenceAverage


ReferencePrecision(%RSD)

KabisPercent

Difference

11DCE 35 71.2 4.2 31.9 18.2 12391 23.4 9.8 13.3 11.6 75

12DCA 35 102.3 14.9 38.7 18.1 16491 32.7 18.2 14.2 16.7 130

BNZ 35 85.6 5.3 37.6 29.0 12791 28.2 12.4 13.7 6.7 106

TCE 35 67.7 11.5 33.2 2.9 10491 25.5 18.0 13.8 12.6 85

112TCA 35 102.2 20.2 41.1 7.7 14991 43.3 19.9 15.1 10.6 187

PCE 35 83.1 6.3 51.8 9.6 16091 31.0 13.6 22.5 7.0 38

19

Table 8. Kabis Sampler and Reference Pump Results from Groundwater MonitoringWells

Well No. KabisAverage TCE


KabisPrecision(%RSD)

ReferenceAverage TCE


ReferencePrecision(%RSD)

06-11 MW 386 3.5 480 5.106-04 MW 338 14.7 596 6.412-09 MW 11.2 10.8 11.2 10.806-2 MW ND (<5) -- ND (<5) --

Note: ND = not detected.

The data in Table 8 reveal that sampler precisionin the field was similar to that observed at thestandpipe. No assurances can be given that theconcentration of TCE in the well was stable overthe duration of the sampling event in each well;thus formal comparisons between the two sets ofdata are not done. Both the Kabis sampler and thereference pump samples were nondetectable forthe well with no TCE. These blank resultsindicate that the Kabis sampler, whendecontaminated using normal procedures, is not apotential source of contamination in low-levelsampling operations.

Sampler VersatilityThe performance parameters for the Kabis samplerdiscussed previously reveal that it can collectwater samples contaminated with VOCs ofvarying volatility at a range of sampling depths.However, some evidence of a significantsystematic bias is observed when results arecompared with those of a reference method.Evidence of negative sampler bias is judged to beof greatest importance since it may result inunderreporting of actual groundwaterconcentrations. Observed cases of negativesampler bias in excess of -25% occur for highconcentrations of PCE and TCE. A statisticallysignificant negative sampler bias of a lessermagnitude is also observed for 11DCE and TCEcases. In light of these considerations, the Kabissampler is judged to have limited versatility.

Deployment LogisticsThe following observations were made duringtesting of the Kabis sampler at both the standpipeand groundwater monitoring wells.• Only one person is required to operate the

sampler. Training requirements are minimal,

with about 1 hour of training required for atechnician to become proficient in routinefield use of the equipment.

• The equipment is lightweight, compact, andrequires no external power to operate.

• A moderate level of manual dexterity isrequired when removing the filled VOA vialsfrom the sampler. Care must be taken to keepboth the sampler and the vials upright whenremoving and capping. Failure to do so mayresult in spilled samples, resulting in unwantedair bubbles in the capped vial. Dexterity isalso required in adding a dilute acidpreservative prior to capping the sample.

• The sampler is designed for portable use atmultiple wells and can be decontaminated inthe field with a detergent rinse followed byseveral distilled water rinses.

• The sampler is maintenance free, with nomoving parts.

• The sampler is not suitable for well purging.In instances where well purging is required, analternative means of purging is required.

• The sampler cannot be used where samplingprotocols require the use of pre-preservedsampling vials or Teflon-lined septum caps invials.

Performance SummaryKabis sampler performance is summarized inTable 9. Categories include precision,comparability with reference method, versatility,and logistical requirements. Cost and physicalcharacteristics of the equipment are also included.

The results of this verification test show that theKabis sampler can be used to collect VOC-contaminated water samples that are statisticallycomparable to a reference method with regard to

20

both precision and accuracy. Some indications ofsignificant sampler bias were observed in selectedtrials. Low recoveries were observed for TCE andPCE at high VOC concentrations at the deeper (91feet) sampling depth evaluated in this study.

The clean-through-dirty trials also gave evidencethat the sampler may carry over contaminantsfrom an overlying dirty layer in a water column.See Section 5 for vendor suggestions to remedythis limitation.

Table 9. Performance Summary for Kabis Sampler

Parameter Summary

Precision For 6 target compounds at low (20 µg/L) and high (200 µg/L) concentrationsand at 17-foot and 91-foot sampling depths:

Relative standard deviation range: 2.9 to 25.8% (reference: 4.1 to 17.6%)

Median relative standard deviation: 10.7% (reference: 8.7%)

In 23 of 24 standpipe test cases, Kabis precision was statistically comparableto the reference sample precision.

Comparability withreference samples

For 6 target compounds at low (20 µg/L) and high (200 µg/L) concentrationsat 17-foot and 91-foot sampling depths, Kabis and reference differences aresummarized as follows:

Percent difference range: −39 to 18%

Median percent difference: −3%

In 16 of 24 standpipe test cases, Kabis differences relative to referencesamples were statistically indistinguishable from 0%.

Statistically significant negative sampler biases in excess of 25% wereobserved for PCE in 2 cases.

Sampler versatility The Kabis sampler demonstrated consistent performance across the testedrange of compound volatility and sampler depth with regard to precision.Some statistically significant sampler biases were observed for PCE andTCE. In light of these biases, the sampler is judged to have limited versatility.

Logistical requirements System can be operated by one person with a few hours of training.

System is lightweight and portable, with no power requirements.

Completeness Sampler was successfully used to collect all of the samples prescribed in thetest plan.

Purchase cost Model I $825

Model II $1,895

Size and weight Model I: 1.75-inch external diam. x 17.4-inch length, 6.5 pounds

Model II 3.56-inch external diam. x 22.3-inch length, 15.5 pounds

Other Sampler cannot be used to purge a well. Other purging system must beprovided if purging is required.

Clean-through-dirty tests reveal that sampler may carryover contaminationfrom an overlying dirty water column into cleaner underlying water. In all testcases, sample recovery in excess of 100% was observed. Sampler percentdifferences, relative to reference samples, ranged from 38-187%.

Note: Target compounds were 1,1-dichloroethene, 1,2-dichloroethane, benzene, trichloroethene, 1,1,2- trichloroethane,and tetrachloroethene.

21

Section 5 – Kabis Sampler Technology Update and RepresentativeApplications

Note: The following comments were provided bythe vendor and have not been verified as a part ofthis ETV test. They have been edited only foreditorial consistency with the rest of the report.

Vendor Observations on Clean-Through-Dirty SamplingThe Kabis Sampler, under certain conditions, mayintake a small amount of air/water interface water,or whatever other liquid may be at the surfaceduring delivery. Fortunately, the sampler flushesthe sample container an average of about six vialvolumes before taking the actual sample. If thesurface layer is composed of extremely highconcentrations, occasionally minute quantities ofthe surface contaminant remain in the sample,possibly giving the indication of a false positive.A field modification that can be performed underthese conditions involves the following: a 3/16 inchID by 2½-inch long piece of Tygon tubing whichhas been heat pinched over a braided nylon cord atone end is lightly pushed over the intake port ofthe Kabis Sampler. Enough cord is included toaccommodate the sampler delivery depth from thesurface. The Tygon tubing effectively seals theintake port from water intrusion until it reaches thedesired sampling depth, at which time the nyloncord is pulled, removing the external plug from thefill port, allowing the sampler's fill cycle to begin.This modification was not employed during theclean-through-dirty field trial of the Kabis Samplerthat was carried out to assess the degree ofcontaminant carryover that occurs when loweringthe sampler through a high VOC concentrationlayer into a low VOC concentration layer.

The Kabis Sampler may be used in nearly anyenvironment. The single exception is an acidenvironment, due to the sampler's stainless steelconstruction. Although the sampler was primarilydesigned for delivery and use in groundwatermonitoring wells, it is equally used in watersupply wells, lakes, rivers, streams, ponds, bays,and in the open ocean. In addition, the KabisSampler has been used with success in storagetanks containing high-energy radionuclides, foodprocessing vats, beer and other beverage processvats, and on a variety of other liquids in variousindustries. Wherever the need to sample liquids ata specific depth is encountered, the Kabis Samplercan be used or adapted for use.

Example Field ApplicationsRecent projects where the Kabis Sampler has beendeployed include chlorinated hydrocarbons atWatervielet Arsenal in New York; DNAPLcontaminants at the Hanford facility inWashington; light fraction hydrocarbons ofgasoline in Raccoon Creek, Pennsylvania; andmethyl-tertiary-butyl ether and perchloratesassociated with rocket fuel production at a formerRocketdyne plant in California. The KabisSampler samples directly into the sample containerunder laminar flow and provides little disturbanceof the well as it is inserted; it is therefore suitablefor sampling dissolved minerals, heavy metals,and salts of all kinds. The Kabis Sampler, becauseof its sampling methodology, cannot be classifiedas a bailer, though it is a grab-type samplingdevice; it is a true discrete-point interval sampler.Its applicability, though, unlike other discrete-interval point samplers, covers a broad range ofenvironments and contaminants.

23

Section 6 − References

EPA, 1996. "Test Methods of Evaluating Solid Waste: Physical Chemical Methods; Third Edition; FinalUpdate III," Report No. EPA SW-846.3-3, Government Printing Office Order No. 955-001-00000-1, Officeof 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. (alsoavailable at http://www.epa.gov/etv/verifrpt.htm#02).

Foster Wheeler, 1998. "Final Hydrogeologic Investigation Report for the National Aeronautics and SpaceAdministration Stennis Space Center, Mississippi," Office of Environmental Engineering, NASA, StennisSpace Center, Mississippi.

Havlicek, L.L, and R. D. Crain, 1988a. Practical Statistics for the Physical Sciences, pp. 202-204. AmericanChemical Society, Washington, DC.

Havlicek, L.L, and R. D. Crain, 1988b. Practical Statistics for the Physical Sciences, pp. 191-194. AmericanChemical 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 SamplingProcedures, US EPA Ground Water Issue (April 1996), Publication No. EPA/540/S-95/504, US EPA OfficeSolid 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).

25

Appendix A — Reference Pump Performance

IntroductionIn addition to the sampling at the standpipe, the verification test design included the collection of vendorsamples from onsite groundwater monitoring wells. During monitoring well sampling, a reference pump wascolocated in the well with the vendor sampler. Both vendor and reference samples were collectedsimultaneously to enable a comparison of the results. This appendix summarizes the reference samplerchosen and outlines its performance and acceptability as a reference sampling technique.

System DescriptionThe reference pump selected for use in this verification study was a submersible electric gear pump (Fultz,Model SP-300, Lewistown, PA). Pump construction materials are stainless steel and Teflon, and pumpdimensions 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 Teflongears inside the cavity push the water to the surface through 100 feet of ¼-inch outside diameter Teflontubing. An electronic controller is used to regulate the flow rate of the pump. Nominal sample collectionflow rates were in the range of 100–200 mL/min.

Performance Evaluation MethodThe gear pump was tested during the standpipe trials in the same manner as the other vendor pumps. Watersamples were collected from the interior of the standpipe in four separate trials with both low (~20 µg/L) andhigh (~200 µg/L) target concentrations at low (17 feet) and high (91 feet) sampling depths (see Section 3 foradditional details). Reference samples were collected from external sampling ports simultaneously with thepump 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 PrecisionA summary of pump precision is given in Table A-1. The percent relative standard deviation results for eachof 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 portprecision data ranged from 2.8 to 16.2%, with a median value of 10.1%. The final column in the table givesthe value of p associated with the F-ratio test (see Section 3 for a description of this test). Values of p lessthan 0.05 may indicate that significant, nonrandom differences exist between the two estimates of precision.

Out of 24 trials, only 2 show values of p less than 0.05. These data indicate that pump precision was notstatistically different from the precision obtained from the reference samples taken directly from the standpipeexternal ports.

26

Table A-1. Precision of Gear Pump and Reference Samples in Standpipe Trials

Compound Conc.Level

Depth(ft)

GearPump

Precision(%RSD)

PortPrecision(%RSD)

F-Ratio F-Ratiop

11DCE Low 17 15.7 14.2 1.11 0.46Low 91 3.5 14.4 14.7 0.01High 17 4.0 8.6 4.81 0.08High 91 7.6 9.7 1.28 0.41

12DCA Low 17 15.4 12.5 2.35 0.21Low 91 3.2 13.2 14.1 0.01High 17 5.1 9.0 3.18 0.14High 91 6.0 10.4 2.38 0.21

BNZ Low 17 8.1 11.8 1.71 0.31Low 91 7.6 12.9 2.30 0.22High 17 3.7 8.4 5.02 0.07High 91 6.1 9.4 1.83 0.29

TCE Low 17 16.3 10.5 2.41 0.21Low 91 5.9 12.1 3.12 0.15High 17 6.4 2.9 4.82 0.08High 91 9.6 8.6 1.55 0.34

112TCA Low 17 9.4 16.2 3.38 0.13Low 91 8.4 15.0 2.81 0.17High 17 7.6 3.5 4.76 0.08High 91 11.0 6.5 3.43 0.13

PCE Low 17 12.9 9.6 1.36 0.39Low 91 9.0 11.7 1.50 0.35High 17 4.5 2.8 2.28 0.22High 91 12.7 8.8 2.38 0.21

Pump Comparability with Reference SamplesGear pump comparability is expressed as the percent difference relative to the reference sample concentrationby subtracting the average reference value from the average gear pump value, dividing the result by theaverage reference value, and multiplying by 100. The percent differences for each of the 24 trials are given inTable A-2. They range from −13 to 14% with a median value of 7%. A t-test for two sample means was usedto evaluate the statistical significance of the differences between the gear pump and reference samples. Thetabulated values of p give a quantitative measure of the significant of the observed difference in probabilisticterms. Values of p less than 0.05 suggest that a statistically significant bias may exist for the trial. With fiveexceptions, all values of p are greater than 0.05, indicating that overall, the differences between the twosampling methods are statistically indistinguishable.

27

Table A-2. Comparability of the Gear Pump with the ReferenceSamples in Standpipe Trials

Compound ConcLevela

Depth(ft)

Difference(%)

t-Testb

p11DCE Low 17 −4 0.64

Low 91 7 0.31High 17 −3 0.54High 91 13 0.05

12DCA Low 17 24 0.05Low 91 10 0.13High 17 −2 0.71High 91 12 0.06

BNZ Low 17 11 0.13Low 91 13 0.11High 17 0 0.98High 91 14 0.03

TCE Low 17 0 0.99Low 91 16 0.04High 17 0 0.95High 91 11 0.10

112TCA Low 17 −6 0.51Low 91 7 0.41High 17 1 0.77High 91 10 0.15

PCE Low 17 −13 0.08Low 91 6 0.37High 17 −6 0.03High 91 6 0.42

a The low-level concentration was in the range of 10 to 20 µg/L for all 6 targetcompounds. The high-level concentration was in the range of 175 to 250 µg/L.

b The t-test was used to compare differences between Well Wizard and reference samplesfor each compound in each trial. Small values of p (<0.05) are shown in bold and aresuggestive of a statistically significant difference. See text for further details.

28

The percent recovery data for the gear pump are also shown graphically by target compound in Figure A-1 foreach of the four standpipe trials. The horizontal dark line in the figure shows the 100% recovery level.

-25

-20

-15

-10

-5

0

5

10

15

20

25

11DCE 12DCA BNZ TCE 112TCA PCE

Compound

~20 µg/L @ 17 ft~200 µg/L @ 91 ft~20 µg/L @ 17 ft~200 µg/L @ 91 ft

Figure A-1. Percent recoveries of the reference pump by compound for the fourstandpipe trials.

Reference Pump Performance SummaryThe test data for the reference pump reveal considerable variability for PCE and 12DCA. However, thevariability and comparability for TCE, the only compound encountered in the field trials, are acceptable. Themean relative standard deviation for TCE was 9.6% and the mean percent difference for TCE was 7%. Thedata presented for TCE show that the pump is equivalent to the reference sampling method in terms of bothprecision and accuracy and is acceptable for use as a reference standard.

29

Appendix B — Quality Summary for Analytical Method

IntroductionAn onsite GC/MS-headspace method was chosen for analysis of all samples in this study. Two identicalGC/MS systems were operated by Field Portable Analytical (Folsom, CA) using a modified EPA Method8260 (for a summary of the method, see Section 3). Data quality measures were incorporated into all onsiteanalyses consistent with the guidelines in Method 8260. This appendix summarizes those data qualitymeasures, thereby demonstrating the adequacy of the method for this verification study.

Data Quality MeasuresA number of data quality measures were used to verify acceptable instrument performance and the adequacyof the final analytical results throughout the course of the study. These measures are summarized in TableB-1. All data quality measures in this table were followed, with the exception of duplicates. Duplicates werenot routinely run since all of the samples from the field were in batches of replicates. Earlier prefielddemonstration studies indicated that the field replicates were the same in composition so that they could betreated as analysis duplicates.

Table B-1. Onsite GC/MS-Headspace Method Quality Control Measures

Quality ControlCheck

MinimumFrequency

AcceptanceCriteria

CorrectiveAction

MS tune check w/bromofluorobenzene(BFB)

Every 12 hours Ion abundance criteriaas described in EPAMethod TO-14

1) Reanalyze BFB2) Adjust tune until

BFB meetscriteria

5-Point (Minimum)calibration

Beginning of each day %RSD ≤ 30% Rerun levels that donot meet criteria

Continuing calibrationcheck (CCC)

Beginning of each day ± 25% difference ofthe expectedconcentrationfor the CCCcompounds

1) Repeat analysis2) Prepare and run

new standardfrom stock

3) RecalibrateEnd calibrationchecks

End of each day ± 25% RPD of thebeginning CCC

1) Repeat analysis2) If end check is out, flag data for that day

Duplicates 10% of the samples Relative percentdifference ≤ 30%

1) Analyze a thirdaliquot

2) Flag reporteddata

Method blanks After beginning of dayCCC

Concentrations for allcalibrated compounds< practicalquantification level

Rerun blanks untilcriteria are met

Data Quality ExamplesThe following data are examples of system performance throughout the course of the study. In the interest ofbrevity, all quality control data are not shown in this appendix. A complete tabulation of all quality controldata is included in the GW SAMPLING DATA NOTEBOOK and is available for viewing through a requestto the ETV Site Characterization and Monitoring Pilot Project Officer.

30

Method Blank CheckMethod blanks were run at the beginning of each 12-hour analysis session. Concentration levels of the sixtarget compounds were reported as ND <5 µg/L for all method blank samples.

Continuing Calibration CheckThe method criterion for the continuing calibration checks run at the beginning and end of each analysis cyclewas a value within 25% of the expected value. The results of the TCE continuing calibration checks for bothof the GC/MS instruments used in the study are shown in Figures B-1 and B-2. Similarly, the results of thePCE continuing calibration check for both instruments are shown in Figures B-3 and B-4. All checkcompound recoveries fall within the predefined control interval of 70 to 130%. The control interval isspecified in EPA Method SW-846, from which this method is adapted. The relative percent differencesbetween the pre- and postanalysis batch calibration check samples are shown in Figure B-5. In two cases, therelative 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 ChartTCE Check Standard

60

70

80

90

100

110

120

130

140

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

12-hr Start

12-hr End

Upper Control Limit

Lower Control Limit

Figure B-1. Calibration check control chart for TCE on GC/MS #1.

31

GCMS (Taz) Control ChartTCE Check Standard

60

70

80

90

100

110

120

130

140

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

Ch

eck

Sta

nd

ard

Rec

ove

ry, %

StartEnd

Upper Control Limit

Lower Control Limit

Figure B-2. Calibration check control chart for TCE on GC/MS #2.

GCMS (Pepe) Control ChartPCE Check Standard

60

70

80

90

100

110

120

130

140

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

Ch

eck

Sta

nd

ard

Rec

ove

ry, %

Series1Series2

Lower Control Limit

Upper Control Limit

Figure B-3. Calibration check control chart for PCE on GC/MS #1.

32

GCMS (Taz) Control Chart

60

70

80

90

100

110

120

130

140

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

Ch

eck

Sta

nd

ard

Rec

ove

ry, %

StartEnd

Upper Control Limit

Lower Control Limit

Figure B-4. Calibration check control chart for PCE on GC/MS #2.

Figure B-5. GC/MS system check relative percent differences.

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