Protocols for Use of Five Passive Samplers Welcome - CLU-IN

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Protocols for Use of Five Passive Samplers

ITRC Protocols for Use of Five Passive Samplers to Sample for a Variety of Contaminants in Groundwater (DSP-5, 2007)

Welcome – Thanks for joining us.ITRC’s Internet-based Training Program

This training is co-sponsored by the US EPA Office of Superfund Remediation and Technology Innovation

All groundwater samplers or sampling methodologies attempt to collect a well-water sample which is representative of the groundwater adjacent to the well. The ITRC Passive Sampler Team has defined a passive groundwater sampler as one that is able to acquire a sample from a discrete position in a well without active media transport induced by pumping or purge techniques. Passive sampling is synonymous with no-purge sampling and can be used as a substitute or replacement for any current groundwater sampling technology. Passive samplers have been used in every state in the U.S. and in many other countries. Passive samplers are easy to use; eliminate purge-water production (therefore, there is little or no disposal cost); reduce field sampling variability resulting in highly reproducible data; decrease field labor and project management costs for long-term monitoring; allow rapid field sample collection; sample discrete intervals in a well; are practical for use where access is difficult or discretion is desirable; can be deployed in series to provide a vertical contaminant profile; and have virtually no depth limit.This training supports the understanding and use of the ITRC Protocols for Use of Five Passive Samplers to Sample for a Variety of Contaminants in Groundwater (DSP-5, 2007). The five technologies included in this document include diffusion samplers (Regenerated Cellulose Dialysis Membrane Sampler and Rigid Porous Polyethylene Sampler), equilibrated grab samplers (Snap Sampler™ and HydraSleeve™ Sampler); and an accumulation sampler (GORE™ Module). The training starts with information common to all five samples then focuses on each sampler as instructors describe the sampler and explain how it works; discuss deployment and retrieval of the sampler; highlight advantages and limitations; and present results of data comparison studies.ITRC (Interstate Technology and Regulatory Council) www.itrcweb.orgTraining Co-Sponsored by: US EPA Office of Superfund Remediation and Technology Innovation (www.clu-in.org) ITRC Training Program: [email protected]; Phone: 402-201-2419

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2 ITRC (www.itrcweb.org) – Shaping the Future of Regulatory Acceptance

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The Interstate Technology and Regulatory Council (ITRC) is a state-led coalition of regulators, industry experts, citizen stakeholders, academia and federal partners that work to achieve regulatory acceptance of environmental technologies and innovative approaches. ITRC consists of 49 states (and the District of Columbia) that work to break down barriers and reduce compliance costs, making it easier to use new technologies and helping states maximize resources. ITRC brings together a diverse mix of environmental experts and stakeholders from both the public and private sectors to broaden and deepen technical knowledge and advance the regulatory acceptance of environmental technologies. Together, we’re building the environmental community’s ability to expedite quality decision making while protecting human health and the environment. With our network of organizations and individuals throughout the environmental community, ITRC is a unique catalyst for dialogue between regulators and the regulated community.For a state to be a member of ITRC their environmental agency must designate a State Point of Contact. To find out who your State POC is check out the “contacts” section at www.itrcweb.org. Also, click on “membership” to learn how you can become a member of an ITRC Technical Team.

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ITRC Disclaimer and Copyright

Although the information in this ITRC training is believed to be reliable and accurate, the training and all material set forth within are provided without warranties of any kind, either express or implied, including but not limited to warranties of the accuracy, currency, or completeness of information contained in the training or the suitability of the information contained in the training for any particular purpose. ITRC recommends consulting applicable standards, laws, regulations, suppliers of materials, and material safety data sheets for information concerning safety and health risks and precautions and compliance with then-applicable laws and regulations. ECOS, ERIS, and ITRC shall not be liable for any direct, indirect, incidental, special, consequential, or punitive damages arising out of the use of any information, apparatus, method, or process discussed in ITRC training, including claims for damages arising out of any conflict between this the training and any laws, regulations, and/or ordinances. ECOS, ERIS, and ITRC do not endorse or recommend the use of, nor do they attempt to determine the merits of, any specific technology or technology provider through ITRC training or publication of guidancedocuments or any other ITRC document.

Copyright 2007 Interstate Technology & Regulatory Council, 444 North Capitol Street, NW, Suite 445, Washington, DC 20001

Here’s the lawyer’s fine print. I’ll let you read it yourself, but what it says briefly is:•We try to be as accurate and reliable as possible, but we do not warrantee this material.•How you use it is your responsibility, not ours.•We recommend you check with the local and state laws and experts. •Although we discuss various technologies, processes, and vendor’s products, we are not endorsing any of them.•Finally, if you want to use ITRC information, you should ask our permission.

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4ITRC Course Topics Planned for 2008 –More information at www.itrcweb.org

Bioremediation of DNAPLsDecontamination and Decommissioning of Radiologically-Contaminated FacilitiesEnhanced Attenuation: Chlorinated SolventsPerformance-based Environmental ManagementPhytotechnologyQuality Consideration for Munitions ResponseRemediation Technologies for Perchlorate Contamination in Groundwater and Drinking WaterSensorsSurvey of Munitions Response TechnologiesMore in development…

Characterization, Design, Construction, and Monitoring of Bioreactor LandfillsDirect Push Well Technology for Long-term MonitoringEvaluate, Optimize, or End Post-Closure Care at MSW LandfillsPerchlorate: Overview of Issues, Status and Remedial OptionsPlanning & Promoting Ecological Re-use of Remediated SitesProtocol for Use of Five Passive SamplersReal-Time Measurement of Radionuclides in SoilRemediation Process Optimization Advanced TrainingRisk Assessment and Risk ManagementVapor Intrusion Pathway: A Practical Guideline

New in 2008Popular courses from 2007

More details and schedules are available from www.itrcweb.org under “Internet-based Training.”

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Logistical Reminders

• Phone line audienceKeep phone on mute*6 to mute, *7 to un-mute to ask question during designated periodsDo NOT put call on hold

• Simulcast audienceUse at the top of each slide to submit questions

• Course time = 2¼ hours

Protocols for Use of Five Passive Samplers

Presentation Overview• Introduction to passive (no-

purge) sampling• Advantages/limitations• General considerations when

using passive samplers • Regulatory perspectives• Questions and answers• Technical aspects for five

passive samplers• Links to additional resources• Your feedback• Questions and answers

No associated notes.

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Meet the ITRC Instructors

Kimberly WardNew Jersey Department of Environmental ProtectionTrenton, New [email protected]

Hugh RieckUS Army Corps of EngineersOmaha, [email protected]

Louise ParkerU.S. Army Engineer Research and

Development CenterHanover, New [email protected]

Kimberly Ward is a Senior Geologist with the New Jersey Department of Environmental Protection (NJDEP) in the Site Remediation Program in Trenton, New Jersey. Before joining the NJDEP, Kimberly worked for five years as a geologist with private environmental consulting companies located in Philadelphia, New Jersey, and Maryland, where she became familiar with various environmental regulations and guidelines associated with groundwater sampling. In 2000, she was hired as a regulator within the NJDEP Bureau of Groundwater Pollution Assessment, advising consultants and private citizens on how to collect a representative groundwater sample. At this time, she was introduced to the work of the ITRC Passive Sampler Team by a coworker who was deploying polyethylene diffusion bags (PDBs) and the regenerated cellulose dialysis (RCD) samplers to collect pore water from stream sediments. Kimberly 's interest led her to become a co-leader of the ITRC Diffusion/Passive Sampler Team in 2004. She currently investigates unknown sources of groundwater contamination for the NJDEP Bureau of Environmental Measures and Site Assessment (BEMSA) and has taken over as Team Leader. She has helped the team develop two ITRC-supported technical documents and speaks, on behalf of the team, on the value and usefulness of passive sampling technologies at various conferences across the country. Her goal for the team is to help identify the validity of passive sampling approaches to the regulatory and consulting communities to the point that these technologies are not considered "innovative" sampling techniques but are accepted approaches to collect groundwater samples. Kimberly earned a bachelor's degree in geological science from Pennsylvania State University in State College, Pennsylvania in 1998. Hugh Rieck is a geologist with the US Army Corps of Engineers - Hazardous, Toxic, and Radioactive Waste Center of Expertise (HTRW-CX) in Omaha, Nebraska. Before joining the HTRW-CX in 2006, Hugh worked six years as a hydrologist with the Arizona Department of Environmental Quality Superfund Programs Section, where he became interested in problems of groundwater sampling for environmental investigations. He began his involvement with the ITRC Diffusion/Passive Sampling team shortly after its inception in 2001 and was an alternate instructor for the ITRC Internet-based training course for the use of polyethylene-based passive diffusion bag (PDB) samplers in 2003. Prior to his state regulatory experience, Hugh worked 13 years as a research geologist with the U.S. Geological Survey, where he specialized in the application of paleomagnetic stratigraphy to investigations of geologic records of climate change. He earned a bachelor's degree in 1974 and master's degree in 1983 in geology and earth science from Northern Arizona University in Flagstaff, Arizona. Louise Parker has been a Research Physical Scientist at the U.S. Army Engineer Research and Development Center's Cold Regions Research and Engineering Laboratory (ERDC-CRREL) in Hanover, NH for over 25 years. She has a broad background in environmental chemistry and microbiology. Since the early 1990s, her primary research focus has been groundwater monitoring and sampling, and analyte/material interactions, with over 60 publications, presentations, and workshops. Recent research studies have examined the suitability of direct-push (DP) monitoring wells for long-term monitoring and passive groundwater sampling methods. Older studies examined sorption of organic contaminants and leaching of constituents by sampling and well casing materials, decontamination ofsampling devices, and the affects of harsh environments on sampling and well casing materials. Since 2002, she has been a member of the ITRC Sampling, Characterization, and Monitoring Team, where she has worked on a technical regulatory document on the use DP wells. Since 2003, she has also a member of the ITRC Diffusion/Passive Sampler team, where she has worked on an overview document on passive groundwater sampling techniques and a technical regulatory document on five passive groundwater sampling methods. Louise earned a bachelor's degree in microbiology from the University of New Hampshire in Durham, NH in 1972 and a master's degree in food science from the University of Massachusetts in Amherst, MA in 1979.

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What you will learn…

What is passive sampling?What passive samplers offer• Quantitative data• Cost savings (40-70%)

How passive samplers reflect aquifer conditions Technical and regulatory guidanceAcceptance of passive samplingClasses and types of passive samplers

The Team defines passive sampler as a device that collects a sample of water, or selectively targeted constituents of water, from a specific depth interval in well (or other location), under ambient conditions (i.e. without the use of a pump). Use of the sampler does not affect the conditions in the well or the sampled medium.

Passive samplers can collect information about aquifer conditions and contaminant migration by different mechanisms than conventional active (i.e. pumped) sampling techniques. They can provide information that would be cost-prohibitive by any other means. In environmental investigations, passive samplers can often replace conventional sampling methods to collect groundwater samples that will meet Data Quality Objectives at significantly lower cost. The principal exception being drinking water quality compliance; therefore they are not recommended for drinking water sampling.

All passive (no-purge) samplers collect quantitative data. The principal distinguishing aspect of passive samplers is that they collect information about conditions at a specific depth within a well. In contrast, pumped samples (low-flow or high volume purge) actively draws in water from above, below and/or adjacent to the screened interval; therefore, collect a flow-weighted average groundwater sample. Passive Samplers:

Do not rely on purge samplingSave money and time since no purge water disposal costs.Are depth-specific; therefore; can profile contaminant concentrations within the screened interval of a well which can aid in refining your Site Conceptual Model, targeting monitoring, and Remedial Process Optimization.

ITRC and other references give Technical and Regulatory Guidance on the applicability, usability and value of passive sampling, and provide a basis for consultants and regulators to evaluate passive samplers for their appropriate application. The team has identified three classes of passive groundwater sampling devices, based on their underlying operating mechanisms. The five most mature examples of passive samplers samplers covered in this document and training represent all three classes.

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Passive Sampler Team

Diffusion Sampler Team formed in 2000Initial goal • Develop guidance on polyethylene diffusion bags (PDBs) for

collection of volatile organic compounds (VOCs) in groundwater1st passive sampling device - diffusion type sampler (DSP-3)Limited in analyte capabilities Increased interest and development of passive devices

Transition to “Passive Sampler Team” • What technologies are being developed and what they can do? • Disseminate guidance on passive sampling technologies• Be premier resource on the use of passive sampling technologies• Promote adoption of regulatory guidance (i.e., acceptance)

The ITRC Diffusion Sampler Team was formed in 2000 and currently is known as the ITRC Passive Sampler Team. This name change occurred in the beginning of 2006 when the team recognized that passive sampler technologies were being validated in lab and field studies and starting to replace the traditional sampling methods. Passive methods will not entirely replace conventional pumped sampling in all situations – for example, initial “broad-brush” site reconnaissance scale sampling, or drinking water compliance, but will rather complement and refine data from pumped methods, usually at substantially lower per-sample cost. The ITRC Passive Sampler Team Technical and Regulatory Guidance has been used to provide a basis for acceptance of passive sampling techniques. There is growing confidence and acceptance of passive sampling techniques, particularly in the last five years, among regulatory agencies, consultants, and their clients as awareness increases and understanding of how they work, how to use them correctly (including better definition of the sampling objectives, sampling plan strategies, and field techniques), how to interpret the data (what the data represent). Passive samplers, including the well-known polyethylene diffusion bag (PDB), have been deployed at sites in every state across the country. More rapid acceptance has been hindered by a lack of understanding of the reasons for, or discomfort with differences between results by different methods, particularly between passive samples and historical pumped data. The field of groundwater sampling has broadened by the development of passive sampling techniques. There is a changing paradigm in groundwater sampling for environmental investigations.The emergence and development of a variety of passive groundwater sampling techniques during the last decade or so is providing data of focus, reproducibility, and ability to target objectives that we’ve not typically had available to us before (at least not without extraordinary effort and expense). Data generated by passive sampling techniques can be more informative, more consistent, and quite often acquired at a much lower “per-sample” cost than conventional or low-flow pumped samples. However, passive sampling techniques represent groundwater conditions somewhat differently than pumped samples, and are driving a need to re-examine our understanding and interpretation of all groundwater sampling data, including seldom considered biases inherent in historical pump and purge sampling, whether low-flow or high flow 3-casing volume purge. The team continues to focus on these goals by updating their website with new research on these technologies and maintaining a contact list with the representatives of the team on the ITRC Diffusion Sampler Information Center (http://diffusionsampler.itrcweb.org).

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9 What Does a Purge Sample Represent?

Active transport of water induced either by pumping or hand-purgingOften draws water from above and below as well as adjacent to the screened interval/open boreholeFlow-weighted average• Based on indicator parameter stabilization or evacuation of

the sampling system (i.e., volume purge)• Gas exchange and mixing

May elevate turbidity • Mobilization of colloids and sediment • Mobilization of normally immobile NAPL microglobules

Compliance with drinking water standards

The ITRC Diffusion/Passive Sampler Team recognized that passive sampler technologies were being validated in lab and field studies and starting to replace the traditional sampling methods. Passive methods will not entirely replace conventional pumped sampling in all situations – for example, initial “broad-brush” site reconnaissance scale sampling, or drinking water compliance, but will rather complement and refine data from pumped methods, usually at substantially lower per-sample cost.

Purge sampling defined as:* 3-volume purging: volume based purge with pump equipment or hand-bailing* low-flow purge: parameter stabilization based purge , no volume restrictions, only flow restrictions and parameter identifiers that determine when to collect a sample

Field experiments, laboratory simulations and numerical modeling support the position that samples are derived from the entire screen zone under low-flow pumping conditions. Varljen, et. al. 2006

Describe the physical aspect of collecting a sample by purging vs passive for various compliance levels

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10 What Does a Passive Sample Represent?

No active transport of water induced by pumping or purgingSamples are collected from a specific depth Rely on sampling device and well water being in ambient equilibrium with the formation water during deployment periodReduce disturbance to the well and aquifer typically caused by bailing or over-pumpingReduce turbidity• Represent “natural conditions”

To retain consistency throughout the training module and published documents, the team has used the above general definitions that are used throughout the documents and training modules. The Team uses the term “passive” synonymously with “no-purge”.

Unfiltered samples can be used to get a better estimation of the true mobile contaminant load.

The emergence and development of a variety of passive groundwater sampling techniques during the last decade or so is providing data of focus, reproducibility, and ability to target objectives that we’ve not typically had available to us before (at least not without extraordinary effort and expense). Data generated by passive sampling techniques can be more informative, more consistent, and quite often acquired at a much lower “per-sample” cost than conventional or low-flow pumped samples. However, passive sampling techniques represent groundwater conditions very differently than pumped samples, and are driving a need to re-examine our understanding and interpretation of all groundwater sampling data, including seldom considered biases inherent in historical pump and purge sampling, whether low-flow or high flow 3-casing volume purge.

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Advantages of Passive Samplers

Highly reproducible data Provides low turbidity samplesDisposable/dedicated - no decontamination between wellsDecrease costs • Field labor ↓

Rapid field deployment and collectionLeave in quarterly

• Little or no disposal cost (no purge-water)Samples discrete intervals • Vertical contaminant profiling • Monitor zone of highest contaminant influx

Easy to use – hand operated with minimal equipment needsNo depth limit

Advantages apply to all 5 technologies discussed in this ITRC Protocol Document (DSP-5) and training module. None of these passive sampling devices use moving parts, they are easy to handle, carry, and deploy since they have minimal equipment needs. Due to their ease of use, passive devices can be valuable tools when you need to sample areas where there is difficult access or when you desire discretion.

To-date, no depth limit has been identified by the Team. Passive sampling devices have been deployed in wells up to 700-feet below ground surface. Passive technologies have replaced low-flow sampling techniques due to depth limitations with pumps sampling at depth under low-flow pump rates. For example, a groundwater sampling projects was using low-flow to sample wells 100-feet or less deep; however, there where problems with the pumps sampling at a low-flow rate at depths greater than 100-feet so passive sampling device was used to sample wells greater than 100-feet deep to supplement low-flow sampling techniques.

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Limitations of Passive Samplers

May have volume/analyte limitationsRequire consideration of contaminant stratification Well must restabilize before sample collection

Limitations apply to all 5 technologies discussed in this ITRC Protocol Document (DSP-5) and training module.

As in all groundwater sampling events, these samplers may require special consideration in wells having a layer of free product [re: sample integrity]

Other consideration to be addressed by any sampler that are not considered limitations but deployment considerations that may affect the quality of the sample collected by the sampler:

- must be submerged in the screened interval during deployment- require the aquifer be in hydraulic communication with the screened portion of the well

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Passive Sampler Team Publications

User’s Guide for Polyethylene-Based Passive Diffusion Bag Samplers to Obtain VOC Concentrations in Wells (March 2001, DSP-1)• Jointly developed with USGS• Basic principles for deployment

Technical and Regulatory Guidance for Using Polyethylene Diffusion Bag Samplers to Monitor VOCs in Groundwater (February 2004, DSP-3)• Easy to use for groundwater and surface water• Quantify savings (40-70%)

Technology Overview of Passive Sampler Technologies (March 2006, DSP-4)• Main application was groundwater sampling• Summarized 12 passive sampling technologies

ITRC Protocols for Use of Five Passive Samplers to Sample for a Variety of Contaminants in Groundwater (February 2007, DSP-5 )• Details on “mature” passive sampling technologies from Overview Document

(DSP-4)www.diffusionsampler.itrcweb.org

The Team initially had coordinated an effort with USGS to assess the applicability of one type of passive sampler - the Polyethylene Diffusion Bag (PDB). Basically, DSP-1 was the first document the Team had worked on together. The Team used the research and the USGS organization to collect and analyze information regarding the use and value of the PDB to assist in groundwater sampling projects for limited volatile organic compounds (VOCs). Basically, replace purge sampling techniques for VOCs only. The issuance of this USGS research led to the Teams first Tech Reg document and Internet Training. In addition, led to the development of the Diffusion Sampler website as a forum to discuss the PDB.

The Guidance on Polyethylene Diffusion Bags (DSP-3) provides basic principles of passive sampling and general considerations that should be made when performing any groundwater sampling event. An archive of the associated ITRC Internet-based training, titled “Passive Diffusion Bag Samplers for Volatile Organic Compounds in Groundwater” is available at http://www.clu-in.org/conf/itrc/diffusion_092503/.

The Overview Document (DSP-4) was generated to provide a summary of developing and mature passive sampler technologies that were being used to sample groundwater. This document provides general information on technologies such as development status, cost, applicability, case studies, vender information, etc. Cost information is available in Table 14-3. Technology availability and cost.

These documents provide background and studies which are a good reference if you are not familiar with passive sampling. ITRC’s Passive Sampler Team documents can be downloaded for free at the ITRC website (www.itrcweb.org) under “Guidance Documents” and “Diffusion Samplers.”

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Classes of Passive Samplers

Diffusion Samplers: analytes reach and maintain equilibrium via diffusion through membrane• Regenerated-Cellulose Dialysis

Membrane (Dialysis) Sampler• Rigid Porous Polyethylene (RPP)

SamplerEquilibrated Grab Samplers: collect a whole-water sample instantaneously• Snap Sampler™• HydraSleeve™ Sampler

Accumulation Sampler: rely on diffusion and sorption to accumulate analytes in sampler• GORE™ Module

Identified more mature technologies from Overview Document (DSP-4)“Maturity” defined as validation of sampler by lab and field testing

Team found that consultants and regulators had questions on how to use technologies so the team decided to provide guidance on using the “mature” technologies from ITRC Overview Document (DSP-4).

This training module is based on the ITRC Protocol Document (DSP-5) and basic principles found in the polyethylene diffusion bag Tech/Reg. Document. (Technical and Regulatory Guidance for Using Polyethylene Diffusion Bag Samplers to Monitor Volatile Organic Compounds in Groundwater (February 2004, DSP-3), available at www.itrcweb.org under “Guidance Documents” and “Diffusion Samplers”)

We try to stress that passive sampling relies on basic groundwater principles that should be considered when performing any sampling event. There is no “special” criteria or studies that need to be performed when implementing general sampling.

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Ambient Flow Through a Well

Relies on flow through in the well screen• Screened zone is in active exchange

with formation waterWater above screen may be “stagnant”References• ASTM, 2002• Powell R.M., and R.W. Puls, 1993• Robin, M.J.L. and R.W. Gillham, 1987

Typical ambient flow in a formation is horizontal. You may not see only horizontal flow within the well. There can be both horizontal and vertical flow components within a screened or open interval. Formation water migrating through the well screen or open interval, reaching equilibrium within the well, may migrate across the well screen to zones of equal or greater zones of hydraulic head.

Contrast ambient with induced flow. Groundwater sampling is performed to collect a sample of formation quality water from the screened or open portion of a well. Induced flow involves the active transport of water, while ambient flow allows water to naturally flow through the formation across a screened interval; therefore, a passive device would represent the water that comes in contact with the device under ambient equilibrium conditions.

General formula used for water in the well to be representative of the aquifer: the rate of solute contribution from the aquifer to the well must equal the rate of in-well contaminant loss, including outflow and volatilization.

•Powell, R.M., and R.W. Puls. 1993. Passive Sampling of Groundwater Monitoring Wells Without Purging: Multilevel Well Chemistry and Tracer Disappearance. Journal of Contaminant Hydrology 12: 51-77.•American Society of Testing Materials (ASTM). 2002. Standard Practice for Low-Flow Purging and Sampling for Wells and Devices Used for Ground-Water Quality Investigations. ASTM Subcommittee D18.21: Designation D 6771-02.•Robin, M.J.L. and R.W. Gillham. 1987. Field Evaluation of Well Purging Procedures. Ground Water Monitoring Review 7, no. 4: 85-93.

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General Deployment

Device suitable for analytes of interestSample volume • i.e., QA/QC and duplicates• Appendix A: Minimum Volumes

Deployment period• Device and site specific

Well restabilization Sampler equilibration

Deployment depth• Should not be arbitrary

Depends on well or site specific data quality objectives (DQOs)

• Sampler represents a depth interval

These are general considerations before the selection or deployment of a passive sampling technology. Retrieval considerations should point out a prompt transfer of sample to sampler container once extracted from the well.

Deployment period = the period of time that accounts for both restabilization of the well and the equilibration of the well water and sampler materials

Restabilization = the period of time well water requires to reach its ambient state following physical agitation Equilibration = the period of time required for well water and or sampler material to

reach chemical equilibrium with the formation water

Team’s general consensus is that the deployment period is a minimum of 2 weeks which is a conservative estimate to cover most restabilization and equilibration time considering most groundwater conditions; however, specific samplers and specific conditions might accommodate less deployment times.•e.g. Longer deployment times should be considered for low-yield wells to account for a longer restabilization period once a sampler is introduced into the well. Passive samplers may be a practical approach since they...

•do not pump, drawing in contamination from other zones or dry out well•displace water but can collect sample within interval

Team has prepared a “Limited Volumes for Analysis” table with minimum volume requirements, if volume is a concern. Available in Appendix A of “ITRC Protocols for Use of Five Passive Samplers to Sample for a Variety of Contaminants in Groundwater” (DSP-5, 2007). ITRC’s Passive Sampler team documents are available at the ITRC website (www.itrcweb.org) under “Guidance Documents” and “Diffusion Samplers.”

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Contaminant Stratification

Stratification is well-specific

Majority of wells are not stratified

Contaminant stratification in an aquifer

vs. in the well

You can have:Stratified or unstratified contaminant distributions in aquifersContaminant concentrations in the well may not reflect the same stratification in the aquifer due to vertical flow.

Unstratified aquifers will yield unstratified wells. This drawing shows stratified contaminants flowing to a well.•For stratified contaminant distributions in aquifers, some wells show contaminants that tend to maintain their position in the well (e.g. BTEX toward the water table—point to upper contaminant zone or dense contaminant could sink to bottom—point to lower contaminant); •Stratified contaminants can also disperse and diffuse while in the open well bore, which tends to flow-weight and average the contaminant concentrations (a flow-weighted average of the influx of clean and contaminated water--point to clean and contaminated water entering the well)•Stratified contaminants can also redistribute by vertical pressure differentials (in this picture, an upward gradient might be reflected by a clean zone below the level of the contaminant plume)

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Contaminant Stratification (continued)

No stratification

0

Total BTEX Concentration (mg/L)

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400 800 1200

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Water Table

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PDB SamplesPurge Sample

Stratification in a well

Dep

th (f

eet)

Toluene (µg/L)0 20 40 60

Dep

th (f

eet b

elow

top

of c

asin

g)

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PDBsamples

Low-flowsample

PDB = Polyethylene Diffusion Bag

Diagram A: Lack of stratification in the well may be due to the presence of vertical flow or reflect uniform contaminant distribution in the aquifer.

Diagram B: Stratification was identified in the well screen. Longer screened or open intervals increase the likelihood of stratification.

Pumped samples would not be able to identify stratification since it collects a flow-weighted average concentration from zones above and below the intake point.

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Contaminant Distribution

Multiple samplers deployed through screened or open interval • Can represent contaminant concentrations over water column

Vertical flow profiling, depending data quality objectives (DQOs), determines primary input/exit of groundwater flow • Borehole flowmeter• Interval packer/pump tests

Profiling techniques can aid in• Refining site conceptual model • Remedial process optimization (RPO)

Profiling techniques• Target a specific depth interval• Can monitor interval with highest concentration

Conservative approach for long-term monitoring

Groundwater sampling is performed to collect a sample of formation quality water from the screened or open portion of a well.

To lower the cost of multiple vertical profile samples, samples can be analyzed with field analytical screening tools or by a certified laboratory for appropriate indicator parameters.

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Data Quality Objectives (DQOs)

Prior to implementation, all parties should agree on DQOsFor instance• Vertical contaminant distribution may be a DQO

so multiple samplers deployed in a well may be advised (vertical profiling)

• Long-term monitoring projects, a single sampler may be appropriate for the DQO

Is your sampling method meeting the DQOs?Do all parties agree?

Site-specific DQOs guide the design of sampling programs including the selection of sampling devices.

Because of these potential differences, it is essential that all parties involved in the implementation of passive samplers at regulated sites identify and agree on DQOs, data evaluation techniques, and data end use beforehand.

If acceptance criteria are met, then a passive sampler may be approved for use in that well. Low-temporal concentration variability: historical sampling results comparisonHigh-temporal concentration variability: side-by-side comparison may be more useful

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DQOs define• Sampling goal• Target analytes• Hydrologic concerns

Pumping methods• Draw groundwater into the well screen

from an undefined area• Example: 3-volume purge and low flow

Passive methods• Discrete vertical and horizontal intervals• Groundwater moves through the well

screen under ambient flow conditions

Pumping moves water toward intake from all points in the flow field, in proportion to

hydraulic conductivity

Pump Intake

Every groundwater sampling technique characterizes contamination differently!

A representative DQO process, as it is used by the Department of Energy (DOE), can be found at http://dqo.pnl.gov/why.htm

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Regulatory Perspective

No regulatory or statutory prohibitions to using passives samplers“De facto” acceptance of passive samplers in 50 states and worldwideNew Jersey Department of Environmental Protection guidance on polyethylene diffusion bags (PDBs) (2005)Five states unofficial guidance (2006) Regulatory agencies use ITRC Polyethylene Diffusion Bag (PDB) guidance for state guidance

Passive samplers have been used

Does your state have any Statutes, Regulations, or Guidance that prohibit or impede the use of passive sampling technologies for the collection of groundwater samples? (16 state responses: Appendix B)

16 States responded (April 14, 2006)The principles of polyethylene diffusion bags (PDBs) are applicable to all passive samples.

While a lack of specific regulatory barriers or prohibitions, and the acknowledgment the de facto use and acceptance of PDBs (and other passive devices) by some regulatory agencies, leaves open the opportunity to use passive samplers, most regulatory agencies remaining silent on the question, and having no official policy or guidance, can itself be a hindrance to their use. This regulatory vacuum needs to be corrected to streamline review and approval of passive sampling proposals and encourage the appropriate use of the best sampling technique to meet data quality objectives by the most efficient means available. Reluctance to use passive samplers may be due in large part to this lack of specific regulatory policy; not everyone wants to be a “pioneer.”

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In Summary

Passive samples collect analytes that come in contact with the sampler under ambient flowValue of passive samplers• Inexpensive • Broad analyte capabilities • Reduced sampler error

Assist in site characterization identifying• Stratification• Target zones for remediation • Migration pathways

1:1 correlation may not occur• Discrete concentration vs. flow weighted concentration• May reflect nature of sampling method

i.e., dilution during purging, pumping versus passive

Tests have shown that contaminant concentrations from the passive samplers adequately represent local ambient conditions within the screened interval despite whether the contaminant concentrations are higher or lower than the conventional method. This result may be because the pumped samples incorporated water containing higher or lower concentrations either from other water-bearing zones not directly adjacent to the well screen (Vroblesky and Petkewich; 2000), or from mixing of chemically stratified zones (Vroblesky and Peters, 2000)

Side-by-side with current sampling method - Deploy pump and passive at same time, retrieving passive sampler first, or- Deploy passive independently, recover immediately prior to placing pump in wellThis method is how the team recommends a side-by-side comparison study; however, this method minimized temporal variability but we can never eliminate spatial variability.

Only about 20% of the comparisons are not 1:1

24

24

Questions and Answers

Covered so farIntroduction to passive (no-purge) samplingAdvantages/limitationsGeneral considerations when using passive samplers Regulatory perspectives

NowQuestions and answers

Next – technical aspects for five passive samplersDiffusion Samplers: analytes reach and maintain equilibrium via diffusion through membrane1. Regenerated-Cellulose Dialysis

Membrane (Dialysis) Sampler2. Rigid Porous Polyethylene (RPP)

SamplerEquilibrated Grab Samplers: collect a whole-water sample instantaneously3. Snap Sampler™4. HydraSleeve™ Sampler

Accumulation Sampler: rely on diffusion and sorption to accumulate analytes in sampler5. GORE™ Module

Questions addressed in this class: What is passive (no-pump) sampling, what passive samples represent, and how do passive sample data compare (or not compare) to pumped sample data? How should we interpret passive sampler data?

Passive samplers have very broad applicability and could be used at every site in the US that collects groundwater samplers. Expanding our sampling toolbox offers the opportunity to select the most cost effective method.

They are not recommended for demonstrating compliance to drinking water standards.

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25

Diffusion Samplers: analytes reach and maintain equilibrium via diffusion through membrane1. Regenerated-Cellulose Dialysis


SamplerEquilibrated Grab Samplers: collect a whole-water sample instantaneously3. Snap Sampler™4. HydraSleeve™ SamplerAccumulation Sampler: rely on diffusion and sorption to accumulate analytes in sampler5. GORE™ Module

Diffusion Samplers


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26

Diffusion Sampler Basics

- Diffusion samplers work because of Fick’s Law of Diffusion.- Fick’s Law basically states that given the proper amount of time, chemical concentrations on either side of a semi-permeable membrane will equilibrate with each other. - For diffusion samplers this means that concentrations of chemicals outside the sampler in the well will eventually equal the concentrations of chemicals inside the sampler.- The concentration gradient across the membrane is what drives the equilibration.- This process is affected by temperature. The warmer the water temperature, the more quickly equilibrium will be achieved.- This process is reversible so eventually volatile constituents can be lost from diffusion samplers if they are not sampled soon after removal from a well. - This principle applies to all types of diffusion samplers. - Membranes may differ but the principle remains the same.

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27

Diffusion Sampler Advantages

Groundwater sampling time in the field is decreased –no pumping neededEliminates purge water and disposal costsExcludes turbidity from groundwater samples – no filtering neededDisposable – no cleaning or cross-contamination

Regenerated CelluloseDialysis Membrane (Dialysis)

Rigid Porous Polyethylene (RPP)

- Several of the general advantages of diffusion samplers were mentioned in the introductory slides but bear repeating.- The sampling time needed in the field to deploy and recover a diffusion sampler is significantly shorter than the time it takes to pump and stabilize a well prior to sample collection. (3x-6x shorter)- This advantage results in a big savings of time for personnel in the field and lowers field sampling costs.- Because the volume of diffusion samplers can be chosen, the amount of excess water collected can easily be minimized. Most or all of the water recovered by a diffusion sampler is collected in sample bottles. Very little if any water is left over to dispose of.- Diffusion sampler membranes have defined pore sizes which are usually smaller than 0.45 microns. Thus, diffusion samplers are themselves essentially big filters, so no field filtering is necessary.- Diffusion samplers are disposable so no cleaning steps are needed and there are no cross-contamination issues between wells.

- Polyethylene diffusion bags (PDBs) have been previously tested and an ITRC document and an online training course has been presented on them. [The document is titled: Technical and Regulatory Guidance for Using Polyethylene Diffusion Bag Samplers to Monitor Volatile Organic Compounds in Groundwater (February 2004, DSP-3). An archive of the associated ITRC Internet-based training, titled “Passive Diffusion Bag Samplers for Volatile Organic Compounds in Groundwater” is available at http://www.clu-in.org/conf/itrc/diffusion_092503/.]- Because polyethylene diffusion samplers are limited to sampling only VOCs, other diffusion samplers have been developed that can sample for all VOCs, inorganic constituents (cations, anions, trace metals, nutrients), and some semi-volatile organics (explosives and dissolved organic carbon).- Two diffusion samplers that I will be talking about today that can sample for these other constituents are the regenerated-cellulose dialysis membrane sampler and the rigid porous polyethylene sampler.

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28 Regenerated-Cellulose Dialysis Membrane Sampler Basics

Referred to as the “Dialysis Sampler”Regenerated-cellulose dialysis membrane• Filled with deionized water• Hydrophilic membrane

Currently must be constructedMembrane sizes• 2.5-inch diameter for 4-inch wells• 1.25-inch diameter for 2-inch wells

Sample volumes• 2.5-inch x 2 ft long contains 2 liters• 1.25-inch x 2 ft long contains 500 mls

Pore size is 18 AngstromsDeveloped by U.S. Geological Survey (USGS)

Fully assembled Dialysis sampler

ready for deployment

- The regenerated-cellulose dialysis membrane diffusion sampler is commonly referred to as simply the “dialysis sampler.”- The sampler is made with a regenerated-cellulose dialysis membrane which is filled with deionized water and suspended in the open interval of a well.- The concentration gradient between dissolved constituents in water outside the membrane vs. the deionized water inside drives diffusion across the membrane.- Because the dialysis membrane is hydrophilic, water molecules, ions, and compounds actually pass through the membrane. [As opposed to the polyethylene membranes which are hydrophobic so water and ions can not pass through them.] - After equilibrium is reached, the sampler is removed and the water inside is sampled.- Currently dialysis samplers are not commercially available so they must be constructed by the user prior to deployment.- Dialysis membrane comes in different sizes – 2.5-inch diameter membrane fits down a 4-inch diameter well; 1.25-inch diameter fits down a 2-inch diameter well.- 2.5-inch diameter by 2 ft long sampler contains ~2 Liters. 1.25-inch diameter by 2 ft long sampler contains ~500 mLs.- Regenerated cellulose membrane has an average pore size of 18 Angstroms (0.0018 microns).- This sampler was first developed about 6 years ago by Imbrigiotta, Ehlke, and Vroblesky, three researchers at the USGS.

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29

Dialysis Equilibration Times

Determined in laboratory in bench-scale tests95% or greater equilibrium reached in dialysis samplers within• 1-7 days for most cations and trace metals• 1-3 days for all VOCs on 8260B list (including

MTBE)• 1-3 days for anions, silica, DOC, CH4, sulfide• 7-14 days for explosives compounds• 28 days or more for Hg, Ag, Sn

- Once deployed in a well, dialysis samplers must be allowed to equilibrate for the appropriate amount of time for the chemicals of interest.- These equilibration times were determined by USGS and US Army researchers in periodically stirred batch tests in the lab, so these times should be worst-case scenarios.- A more detailed list of the parameters tested in the laboratory is given in Table 5-2 in ITRC Protocol Document (DSP-5).- Under field conditions where groundwater is flowing through the open interval, chemical equilibration should occur more quickly.- Most tested chemical constituents take 1 to 14 days to equilibrate. - Only mercury, silver, and tin were found to take longer than 14 days to equilibrate through the regenerated-cellulose membrane.

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30

Dialysis Sampler Advantages

Collects inorganic and organic chemical constituentsQuick equilibration and deployment times –generally 1-2 weeks Relatively inexpensive to constructExcludes turbidity from groundwater samples –no filtering neededCollects relatively large sample volume for a no-purge sampler

- The main advantage over PDBs is that dialysis samplers can collect both organic and inorganic constituents.- Lab testing has shown that most chemical constituents will chemically equilibrate within 1 to 2 weeks through the dialysis membrane.- Therefore total deployment times for a dialysis sampler may be as short as 1-2 weeks depending on the hydrology and chemistry of a well. - Dialysis samplers are slightly more expensive to construct than PDBs but are still inexpensive compared to renting or buying pumps.- Because of their small pore size, dialysis samplers exclude particulates from the collected groundwater sample so no field filtering is needed.- Dialysis samplers collect relatively large sample volumes compared to other no-purge samplers. The volume collected can easily be adjusted by varying the length of the sampler when it is constructed.

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31

Dialysis Sampler Limitations

Samplers must be kept wet between construction and deploymentMembrane can biodegrade within 4-6 weeks• Not a problem for shorter deployments

Samplers lose water volume slowly (<3% per week)• Not a problem for short deployments• Internal support for high ionic strength waters is

available

- Dialysis samplers must be kept hydrated between the time they are constructed and the time they are deployed in a well. If the membrane dries out it turns brittle and can crack. - Regenerated cellulose is a bioactive membrane, that is it is food for some bacteria. These membranes have been shown to biodegrade in test wells within 4 to 6 weeks. The bottom line is that most chemicals tested thus far equilibrate quickly enough through the dialysis membrane so this limitation should not adversely affect their usefulness in sampling in most wells.- Because dialysis is a two-way process, not only are dissolved ions diffusing into the sampler, but water molecules are also diffusing outward in an attempt to dilute the aquifer to distilled water. Fortunately, the gradient for ions diffusing inward is higher that the gradient for water molecules diffusing outward. In general, tests have shown that less than 3% per week of the samplers original volume is lost through this process. This loss may be a more significant problem in high ionic strength waters. An internal support can be inserted inside the dialysis membrane to ensure that a minimum volume of water will still be retained inside the sampler.

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32

Ethylbenzene (µg/L)

0.1

10

1000

0.1 10 1000

LRL

1/2 MDL

Vinyl Chloride

(µg/L)

0.001

0.1

10

1000

0.001 0.1 10 1000

LRL

1/2 MDL

Dialysis Field Comparison Results

Dialysis Sampler

Low

-Flo

w P

urgi

ng

Chloride (mg/L)

0.1

10

1000

0.1 10 1000

LRL1/2 MDL

Manganese (µg/L)

0.1

10

1000

0.1 10 1000

LRL

1/2 MDLFrom: Imbrigiotta et al. (2007)

- These graphs show examples of field comparison results from a study by Imbrigiotta et al. (2007) for one aromatic VOC (ethylbenzene), one chlorinated VOC (vinyl chloride), one anion (chloride), and one cation (manganese).- Each graph shows the concentrations recovered by the dialysis sampler on the x-axis vs. the concentrations recovered by low-flow purging on the y-axis. Each red diamond represents one comparison from one well. If both sampling techniques recover equal concentrations, all red diamonds should be on the 1:1 correspondence line.- The white area of each graph is where concentrations are above the laboratory reporting limit (LRL) for the parameter being shown. The yellow area of the graph is where concentrations are between the reporting limit and one-half the minimum detection limit (1/2 MDL). The pink area of the graph is where concentrations are less than one-half the detection limit.- As you can see for all of the parameters plotted, all graphs show reasonably close agreement between the concentrations recovered by dialysis samplers and low-flow purging. - Deviations, such as those seen at low concentrations for ethylbenzene, are most likely due to water of different chemistry being drawn into the well during purging than was in the open interval during the dialysis sampler equilibration period. In fact, PDB and dialysis sampler VOC results agreed very well in these same wells.

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33 Dialysis Field Comparison Results (Dialysis Samplers vs Purging Methods)

Parameters with favorable results• VOCs• Cations and anions• Most trace metals • Explosive compounds • Others (silica, ethene,

CO2, CH4, TDS, SC, DOC)

Parameters with questionable results• p-Isopropyltoluene• n-Butylbenzene• s-Butylbenzene• Nickel• Sulfide

See Table 5-3 in ITRC Protocols Document (DSP-5)

Field comparisons between dialysis samplers and low-flow purging have found equal recoveries of:•Most chlorinated VOCs (PCE, TCE, cisDCE, DCE, transDCE, VC, 111TCA, 11DCA, CM, Clform, MC, DCDFM, 12DBE)•Most aromatic VOCs (BTEX, Styrene, 124TMB, 135TMB, iso-propylbenzene, t-butylbenzene, n-propylbenzene, Naphthalene)•Ethers (MTBE, 1,4-Dioxane) •Cations and anions (Ca, Mg, Na, K, alkalinity, Cl, SO4, NO3, Br, F)•Most trace metals (Fe, Mn, Al, As, Ba, Cd, Cr, Cu, Mo, Pb, Sb, Se, V, Zn)•Explosive compounds (RDX, HMX)•Silica, ethene, CO2, CH4, TDS, SC, DOC

The only parameters with questionable field comparison results include a few aromatic VOCs, which did compare favorably to PDBs in side by side tests, nickel, which was only present in below reporting limit concentrations, and sulfide which was recovered in equal or higher concentrations in the dialysis sampler than in the low-flow purged samples. More investigation is needed into these last few parameters to determine if these differences are found at other sites.

A more detailed list of parameters is given in Table 5-3 from ITRC Protocols for Use of Five Passive Samplers to Sample for a Variety of Contaminants in Groundwater (DSP-5, 2007) available the ITRC website (www.itrcweb.org) under “Guidance Documents” and “Diffusion Samplers.”

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34

Dialysis Sampler Summary

Collects both organic and inorganic chemical constituentsDo not require filtration of samplesEquilibrate within 1-2 weeks for most constituentsDeployment times 1-2 weeks in most wellsDialysis samplers recover comparable concentrations of • VOCs vs. PDB samplers• VOCs and most inorganics vs. low-flow and purging and sampling

Dialysis samplers should not be used when• Sampling for mercury, silver, or tin• Equilibration will take longer than 4 weeks• Total concentrations are needed

Dialysis samplers should be used with caution when• Sampling for nickel and sulfide

- Dialysis samplers can collect both organic and inorganic chemical constituents in groundwater.

- Dialysis samplers do not require field filtration of samples. They only collect dissolved concentrations.

• Bench-scale testing showed that dialysis samplers chemically equilibrate within 1-2 weeks for most inorganic constituents and VOCs.

• Deployment times in most wells are generally 1-2 weeks.• Field comparisons showed dialysis samplers recover VOCs equal to PDB samplers.- Field comparisons have also shown dialysis samplers recover VOCs and most inorganics equal

to low-flow purging.• Only chemical constituents tested that did not seem to diffuse through the dialysis membrane

were mercury, silver, and tin. Possibly due to the formation of metal-organic complexes that either sorb highly to the membrane or are big enough that they don’t diffuse through very quickly.

- Dialysis samplers should not be used when equilibration times might extent past 4 weeks due to potential biodegradation.

- Dialysis samplers should not be used if total concentrations are required. - Sampling for nickel and sulfide needs to be further tested.

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35 Rigid Porous Polyethylene (RPP) Samplers

Made of hard, porous polyethylenePore sizes 6-15 microns5 inches long1.5 inches in diameterFilled with deionized waterStandard size holds 90-100 mL In protective mesh ready for

deployment and packaged in disposable water-filled

sleeve for shipping

Cap

Delrin plug

The RPP sampler was developed by Don Vroblosky of the USGS.The RPP sampler is constructed of thin sheets of hard-foam-like porous polyethylene with pore size of 6-15 microns. The outside diameter is approximately 1.5 inch. They are 5 inches in length. If made longer, the higher head pressure in the sampler forces the water inside to “leak” out through the pores.They are filled with de-ionized, analyte-free water, capped at one end and a Delrin plug inserted into the other end. The one in the picture on the left is equipped with a second smaller plug. This sampler is for deployments where the analytes of interest are volatile organics. Use of the smaller plug will minimize potential loss of VOCs by any vacuum that may be created by the plug’s removal when sampling into the sample containers.The RPP is placed in a mesh liner so that it may be attached to the deployment line with cable ties.The picture on the right shows an RPP ready for shipment. It comes in a water filled polyethylene bag to ensure that the pores stay water filled. If they become blocked by air bubbles, diffusion of water soluble analytes may not occur.Water soluble analytes pass through the pores until equilibrium is reached with the aquifer immediately adjacent to the well screenIn bench studies, equilibrium time ranged from hours to days, depending on the analyte. The more water soluble the analyte the quicker the equilibrium.A general rule of thumb for all diffusion samplers is they should be deployed not less than 14 days for most analytes. They can be left in the wells for a quarter, but we currently have no data for longer deployments for RPP samplers. These samplers are commercially available through Columbia Analytical Services, Inc. Please see the Protocol Document (DSP-5) for contact information.

36

36 Select RPP Analytes and Equilibration Times

14Dissolved gases

21 (all except silver and copper)

Dissolved metals (priority pollutant list)

21Explosives (i.e. HMX, TNB, RDX and TNT)

14Water soluble SVOCs (i.e. NDMA, phenols)

14Water soluble VOAs (i.e. MTBE, MEK, Acetone, 1,4-Dioxane)

14Methane, ethane, ethene (MEE)

14Perchlorate, chloride, hexavalent chromium, nitrate, sulfate, soluble iron

Equilibration time (days)Analyte

Please see the tables in the Protocol Document (DSP-5) for the actual equilibration data. New analytes are being added as field studies continue. Additional field studies on water insoluble VOCs and SVOCs are needed. In bench studies, the VOCs and SVOCs with low water solubility (please see Tables 6.5 and 6.7 in the Protocol Document (DSP-5)) disappeared from the carboy and were not found in the water in the samplers, leading to the conclusion they were adhering to the sampler itself. It’s thought that with longer equilibration times, the sites on the sampler would become saturated and equilibration would occur, but field studies are needed to confirm this.

ITRC Protocols for Use of Five Passive Samplers to Sample for a Variety of Contaminants in Groundwater (DSP-5, 2006) is available at the ITRC website (www.itrcweb.org) under “Guidance Documents” and “Diffusion Samplers.”

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37

RPP Advantages

Can be used to collect most inorganic and limited organic analytesAre commercially available and field-readyCan be stacked when additional volume needed

RPP Samplers have the same general advantages as other passive samplers:•eliminate purge water collection•are easily deployed and retrieved•reduce field sampling costs significantlyThe RPPs are frequently used with a polyethylene diffusion bag (PDB). The RPPs for inorganics and the PDB for VOAs. RPP and PDBs are currently deployed for 1,4-dioxane and VOCs, respectively.

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38

RPP Limitations

Must be stored and shipped fully immersed in deionized waterHave not been tested for all analytesMultiple samplers are needed to obtain sufficient volume for multiple Analyte types and/or QA/QCRequires advanced analytical techniques to analyze for SVOCsEquilibrium times for less water soluble VOCs and SVOCs are not currently known

To prevent air from blocking the pores RPPs are shipped submerged in water-filled sleeves Wells must be 2 inches or more in diameter to accommodate the diameter of the RPPs.They hold only 90-100 mL of sample; if additional sample volume is needed, multiple RPPs must be stacked.It is very important that you discuss the low sample volume with your laboratory to ensure they can meet your data quality objectives (DQOs). Do they have equipment that will allow them to use less volume that normally requested. For instance, the standard minimum volume required for SVOCs by 8270 is 250 mL. Theoretically, using solid phase extractors and large volume injectors you would need no more than 10 mL of sample, though most labs would still request 50-100 mL of sample if available. A minimum volume table can be downloaded from the ITRC’s Diffusion Sampler website (http://diffusionsampler.itrcweb.org/). The link is located towards the bottom of the home page.It’s not yet known how long it would take for VOCs and SVOCs to equilibrate. Please see the Protocol Document (DSP-5) for additional information about water solubility and equilibrium (Table 6.5).

ITRC Protocols for Use of Five Passive Samplers to Sample for a Variety of Contaminants in Groundwater (DSP-5, 2006) is available at the ITRC website (www.itrcweb.org) under “Guidance Documents” and “Diffusion Samplers.”

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39 McClellan AFB Multi-analyte, Multi-sampler Study (Parsons 2005)

0.001

0.01

0.1

1

10

100

1000

10000

100000

0.001 0.01 0.1 1 10 100 1000 10000 100000

Low-Flow Purge Sample Concentration (µg/L)

RPP

s Sa

mpl

e C

once

ntra

tion

(µg/

L)

Metals:1,4-Dioxane:Anions:Hex Cr:VOCs:

For All Datay = 0.941xR2 = 0.9764

This study compared 4 passive sampling devices and 2 equilibrated grab samplers against low-flow and conventional 3-volume well purging sampling. This graph depicts RPPs against low-flow sample results.

The authors concluded that RPPs “appear to be a technically viable method for monitoring hexavalent chromium, metals and anions. Although concentrations of VOCs and 1,4-dioxane obtained using this method are statistically similar to low-flow concentrations of these analytes, they tended to be biased low relative to concentrations obtained using the three-volume purge method.” 1

Subsequent laboratory studies have shown that RPPs should not be used for VOCs unless further equilibration studies are completed. Subsequent field studies have shown that they may be used for 1.4-dioxane.

1. Parsons. 2005. Results Report for the Demonstration of No-Purge Groundwater Sampling Devices at Former McClellan Air Force Base, California. Prepared for the U.S. Army Corps of Engineers Omaha District, the Air Force Center for Environmental Excellence and the Air Force Real Property Agency. 7-2.

40

40 RPP Representative Field Study for 1,4-Dioxane at a North Carolina Site

Each point on the plot represents a single-constituent data pair of each sampling method.

R2 = 0.9224y = 0.852x

n = 9

0

0.05

0.1

0.15

0.2

0.25

0 0.05 0.1 0.15 0.2 0.25

RPP

(mg/

L)

Low Flow (mg/L)

The interest in RPPs for this particular project was because a number of the wells at this site are very deep (some more than 200 feet). The depth of the well screens was below the low-flow pumps operating capability. The RPPs were tested against low-flow pumps in 10 wells at the site from 23 to 110 feet deep to see how they compared to decide whether they were a viable option for the deep wells. The concentrations of 1,4-Dioxane were low in these wells (0.010 to 0.22 mg/L) with the exception of one well, V-23, where the concentration was approximately 3 mg/L. Including the data from that well gives an R2 of 0.999 and y=1.073x, but the representation puts the lower concentrations quite close together which makes the data points hard to see. This depicts the low concentration well results. The next page depicts the results from all wells.

41

41 RPP Representative Field Study for 1,4-Dioxane at a North Carolina Site

0

0.5

1

1.5

2

2.5

3

0 0.5 1 1.5 2 2.5 3

RPP

(mg/

L)

Low Flow (mg/L)

R2 = 0.999y=1.073x

n=10

Each point on the plot represents a single-constituent data pair of each sampling method.

RPPs are now deployed at this site on an on-going basis. This study may be found in the Protocol document (DSP-5) Section 6.5.2 and Table 6.10.

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42

RPP Summary

Can be used to sample for • Most inorganics• Water soluble VOCs and SVOCs

It’s not currently known if they can be used for water-insoluble VOCs and SVOCsCan be used in deep wells Can be used in conjunction with PDBsInexpensive, disposable sampler• No decontamination required

RPP Samplers may be used to sample for most inorganics, but further studies are needed to determine suitability for some organics, especially less water soluble VOCs and SVOCs.Studies are on-going

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43

Diffusion Sampler Summary

RPP and Dialysis Membrane samplers can be used for VOCs, SVOCs, metals, anions, and cationsDeployment time for RPP and Dialysis sampler is ~2 weeksCompare well with conventional methodsCollect samples at a discrete interval in well screenRPP sampler can be used for quarterly or longer deploymentsMajor limitation of RPP sampler is sample volumeMajor limitation of Dialysis sampler is that it undergoes biodegradation

Regenerated CelluloseDialysis Membrane

Rigid Porous Polyethylene (RPP)

*RPP and Dialysis Membrane Samplers can be used for a much broader range of analytes than the PDB sampler.

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44




Equilibrated Grab Samplers


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45

Equilibrated Grab Samplers

Collects sample from discrete interval in well screenCollect “whole water” samples that can be tested for any analyte Collects samples in “real time”Equilibration period allows• Well to recover from sampler

placement • Materials to equilibrate with

analytes in well waterTechnologies• Snap Sampler™ • HydraSleeve™ Sampler

Snap Sampler™

HydraSleeve™ Sampler

Equilibrated grab samplers are the next class of sampler included in the ITRC Protocol Document (DSP-5).

Typically, these samplers are placed in the well, and left for an equilibration period.After the equilibration period, the sample is collected.

By allowing the well to recover from placing the sampler in the wellyou allow the flow pattern in the well to reestablish itself &you reduce the possibility of falsely elevating turbidity in your samples

through agitation.

By allowing the materials to equilibrate with the analytes in the well water, you eliminate possible biases due to sorption that can occur between some types of analytes and the sampler.

We want to stress that losses due to sorption can occur with any type of sampler (including bailers and the tubing used in e.g. low-flow sampling)

if there is not an adequate equilibration between the analytes and the materials.

Because these samplers do not rely on diffusion or sorption, they can collect a sample on the specified day.

The two devices in this class included in the ITRC Protocol Document (DSP-5) are the HydraSleeve™ Sampler and the Snap Sampler™.Both of these devices are commercially available.

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46

Snap SamplerTM Components

Sampler body with trigger mechanism• 1.6 inches in diameter • Fit in 2-inch wells

Bottles with two openings and spring-activated caps• 40-mL VOA vials• 125-mL polypropylene

bottlesTrigger lineDocking station

125 mL40 mL

Description of the Snap Sampler™ technology can be found in section 4 of the ITRC Protocol Document (DSP-5).

Snap Samplers™ are typically dedicated devices.

Snap Sampler™ bottles are unique in that they have openings on two ends and caps that are connected by an internal Teflon-coated spring.

The trigger line consists of a Teflon-coated wireline cable inside a polyethylene tube.

The bottles are placed in the sampler.The end caps on the bottles are placed in an open position with the release pins on the sampler.The trigger line is attached to the sampler and then used to lower the device into the well.

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47

Snap SamplerTM – Collecting a Sample

Sample bottles deployed in open positionEquilibration period • Minimum of 1 to 2

weeks• Can be used for

quarterly, semi-annual, or annual sampling

Samples sealed in situ No sample transfer required at the surface

Deployment times are at least 1-2 weeks.

The sampler can be used for longer deployments.In those cases, the samplers can be redeployed after the sampling event so that an extra trip to the field is not needed prior to the next sampling event.

Because the sample bottle is closed in the well, there is no chance of interaction of the sample with the water column as the sample is removed from the well.

Upon retrieval, no sample transfer is required. Samples can be sent to the laboratory in the same bottle the sample was collected in.

The 40 ml VOA vials are compatible with common autosampler equipment.

However, acid can be added if preservative is needed without having to open the sample bottle.This procedure is discussed in more detail in the ITRC Protocol Document (DSP-5).

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48

Snap SamplerTM Advantages

No analyte restrictionsReducing the sampling variability • Minimal agitation of well

during sampling• Bottles remain sealed

under in-situ conditions• No sample transfer

No exposure to weather, surface contamination, etc.Reduced losses of volatiles and gases

Because these samples do not agitate the water column, particles from the formation are less likely to be entrained in the samples.

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49

Snap SamplerTM Limitations

Sample can be collected only in available bottle sizes (sample volume is limited)• 40-ml VOA• 125-ml plastic

350-ml plastic in development for 4-inch wells

May not be practical for wells with long analyte listsTrigger lines are fixed length and thus cannot be readily moved to other wells

The primary limitation with this device is sample volume.

This limitation can be overcome in some instances by deploying multiple samplers either on multiple trigger lines or in series on the same trigger line.

Up to 4 samplers can be deployed on the same trigger line.

However, this method may not be practical for long analyte lists where large sample volumes are needed.

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Snap SamplerTM – VOC Field Study

Very good correlationsSlightly higher concentration values with Snap SamplerTM than low-flow and PDB

1

10

100

1000

10000

1 10 100 1000 10000 100000Polyethylene Diffusion Bags (PDBs) and Low Flow VOC results (ppb)

Snap

Sam

pler

™VO

C re

sults

(ppb

)

PDB y=1.126x R2=0.999

n=25

Low Flow y=1.098xR2=0.979

n=9

100000 Chlorinated VOCs (CVOCs), University of Waterloo Study

This study compared the results for chlorinated VOCs using a polyethylene diffusion bags (PDBs) sampler vs. the Snap Sampler™ (green ovals) and low-flow sampling vs. the Snap Sampler™ (brown diamonds).

Each data point on the graph depicts paired data for one sampling method compared with the other for the same chemical constituent in the same well at the same depth.

There was a very good correlation (as shown by the high correlation coefficient) between the Snap Sampler™ results and the PDB results, and between the results for Low Flow sampling vs. the Snap Sampler™.

“Y” values (or slope) indicate Snap Sampler™ yields slightly higher concentrations than either the PDB samplers or the low-flow sample.

This difference may be because of the unique features of this sampler, i.e., there is no sample transfer or exposure to the atmosphere.

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51 Snap SamplerTM – Multi-analyte Field Study

Study at former McClellan Air Force Base (Parsons Inc. 2005)

Low-Flow Purge Sample Concentration (µg/L)

Snap

Sam

pler

™ C

once

ntra

tion

(µg/

L)

AnionsAnions

1,4 Dioxane1,4 Dioxane

R2 = 0.99 for all analyte comparisons

to low flow0.01 0.1 1 10 100 1000 10000 100000

100000

10000

1000

100

10

1

0.1

0.01

VOCsVOCs

This study compared several passive sampling methods and two purged sampling methods

Specifically, this study compared 3-well volume purging and low-flow sampling with samples taken using the Snap Sampler™, the HydraSleeve™ Sampler, the PDB sampler, the Dialysis membrane sampler, and the RPP sampler.

Analytes of interest included VOCs, metals, anions, and 1,4-dioxane

Snap Sampler™ showed excellent correlations with both low flow and volume-based purge methods.

Parsons concluded the Snap Sampler™ “…may be more consistently representative of the actual VOC concentrations in the well at the time of sampling….”

All datay=1.2153xR2=0.9916

1,4 Dioxaney=1.2582xR2=0.9991

Anionsy=1.2153xR2=0.9891

VOCsy=1.7719xR2=0.9949

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Snap Sampler™ Summary

Samples are sealed at the point of collection No transfer of sample requiredReduced losses of VOCs• Less variability

Data correlates well with standard sampling methodsVolume limited – but analyte capability not limited

More information on the Snap Sampler™ technology can be found in section 4 of the ITRC Protocol Document (DSP-5).

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HydraSleeve™ Components

Check Valve

Sample Sleeve

Reusable Weight and Clip

Check Valve

Sample Sleeve

Reusable Weight and Clip

Discharge tube

This sampler is simple in design and easy to use.Information on this sampler can be found in Section 3 of the ITRC Protocol Document (DSP-5).

ComponentsPolyethylene sleeveTop loading reed style check valveReusable stainless steal weight and clipDischarge tube

Typical sampler diameters are 1.5 inches (filled), will fit 2-inch wells2.5 inches OD (filled) , will fit 4-inch wellsSmallest diameter available will fit ¾-in wells

To assemble these samplers, simply • Unfold• Clip weight to bottom• Attach tether (line) to top

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HydraSleeve™ Sample Collection

Empty

Full

SampleInterval Filling

To deploy the HydraSleeve™, lower the sampler through the water column.The sampler will remain empty as the sampler is lowered through the water column and will remain empty during the equilibration period.

When it is time to collect a sampler, Pull the HydraSleeve™ upward >1 foot per second (~the speed a bailer is recovered).

Pressure opens reed valve allowing sleeve to move outward to collect the water

In essence you are collecting a “core sample of the water column” and the mechanism is much like pulling on a sock.

When the sampler is full, the reed valve closes, and remains closed as the sampler is recovered from the well and this prevents interaction between the water column and the sample inside the sampler.

Once the sampler is at the surface, the sample should be transferred immediately to the sample bottles.

Sampling interval for a standard sized HS is 1 to 1.5 times the length of the sampler

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HydraSleeve™ Advantages

Fits in most diameter wells Can sample all types of analytes Collects relatively large sample volume • 2-inch HS collects 650 mL• 4-inch HS collects 1250 mL

Simple designEasy to use with minimal trainingCan sample• Very deep wells• Crooked wells

Can collect low turbidity samples

Standard 2-inch HS fits in a 2-inch well (the diameter of this sampler when filled is ~ 1.5 inches) Off the shelf 1-inch HS are available and ¾-inch HS are can be made on request.

Larger samples can be used for low concentrations of contaminants or for multiple analyte types.

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HydraSleeve™ Limitations

Large sample volumes*• Custom samplers can be fabricated in

a wider diameter and/or longer length to maximize sample volume

• Work with lab regarding minimum sample volume

Using table in Appendix A of the ITRC Protocol Document, DSP-5

*True for most passive samplers

* This sampler collects the largest volume of any passive sampler, and in most applications, the sample volume this sampler collects is more than adequate.e.g., the standard 2-inch HS collects 650 mL of sample and the longer 2-inch HS collects a liter of sample

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57

020406080

100120140160

1,1-DCA 1,1-DCE cis-1,2 DCE 1,1,1-TCA TCE Freon 113

HydraSleeve™ – Field Study (1 of 2)

Con

cent

ratio

n (p

pb)

2-inch diameter well in Northern California (Geomatrix Inc., 2000)

HydraSleeve™

Purge/Sample

Good agreement between the VOC concentrations in the purged samples vs. those taken with the HydraSleeve™ Sampler.

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HydraSleeve™ – Field Study (2 of 2)

Comprehensive comparison of • Low-flow and 3-well volume purged samples• Samples collected using 6 no-purge samplers

Analytes included• VOCs, 1,4 dioxane, anions, metals, and hexavalent

chromiumFindings• “The HydraSleeve and Snap SamplerTM produced results

most similar to the higher concentrations obtained by low-flow and 3-well volume purging and sampling methods”

• Other conclusions about the HydraSleeve™ included Was least expensiveSimplest to deploy and retrievePermits larger sample volume“Appears to be a technically viable method for monitoring all of the compounds in the demonstration”

Former McClellan Air Force Base (Parsons Inc., 2005)

Most comprehensive study to date

Available on ITRC Diffusion/Passive Sampler team web site: http://diffusionsampler.itrcweb.org Look under key documents

Polysolfone is #6

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HydraSleeve™ Sampler Summary

Sample all analyte typesCollects relatively large sample volume• For a passive sampler

Can be used in • Deep wells• Crooked wells

Comparable results to conventional pumped methodsCan be left in well for quarterly, semi-annual, or annual samplingDisposable sampler• No decontamination required

Inexpensive to ship (100 samplers will fit in an overnight envelope)

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Equilibrated Grab Samplers Summary

Samples can be analyzed for all analyte types• Providing there is adequate sample volume

Collect whole water samples in real-timeCan be used for quarterly, semi-annual, or annual sampling eventsUse an equilibration period to reduce sampling biasesCollect samples at a discrete interval in well screenCompare well with conventional methodsSimple logistics – no power requirements

Snap Sampler™

HydraSleeve™ Sampler

No associated notes.

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61




Accumulation Samplers


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Accumulation Samplers

Rely on diffusion and sorptionExamples of accumulation samplers• Semi-permeable Membrane Devices (SPMD) • Polar Organic Chemical Integrative Sampler (POCIS)• Passive In-situ Concentration Extraction Sampler (PISCES)• GORE™ Module

More information on other accumulation samplers is available • Overview of Passive Sampler Technologies (March 2006,

DSP-4)• http://diffusionsampler.itrcweb.org/

Accumulation samplers rely on diffusion of the analytes through the membrane and sorption on some type of sorbent material housed within the sampler membrane.

I will discuss the 1 accumulation sampler included in the ITRC Protocol Document (DSP-5), the GORE™ Module.

This sampler is discussed in Section 2 of the ITRC Protocol Document (DSP-5) and is commercially available.

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GORE™ Module Components

GORE™ Module• Section 2 in ITRC Protocol Document

(DSP-5)Attachment Line Stainless steel weights

Knot (secure to wellhead)

Attachment Line

Loop to attach line

Tag with unique serial number

Adsorbent

Weight

This sampler discussed in Section 2 of the ITRC Protocol Document (DSP-5)This sampler is also known as the GORE-SORBER Module (is shown in the figure on the left).

The module itself comes completely assembled in its own sample vial. The module is about the size of a soda pop straw in length and diameter.It consists of a tube made of GORE-TEX® membrane, which is a vapor-permeable, waterproof membrane. Housed within the tube is the adsorbent material.

Each module and glass vial is assigned a unique serial number that is used for sample tracking (Chain of Custody) purposes.

The two figures on the right illustrate the components of the GORE™ Module and its deployment in a well.

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GORE™ Module Sample Collection

Dissolved compounds partition to vapor (Henry’s Law)Diffusion through hydrophobic, vapor-permeable membraneAdsorption onto mediaDuplicate samples

Vapors pass through

Liquid water

remainsoutside

Adsorbents

GORE-TEX® Membrane

The figure on the left shows the membrane at high magnification.The dark areas represent the pore space in the membrane.

The figure on the right shows conceptually how the analytes partition to the vapor phase, and diffuse through the membrane and are then sorbed by the sorbent material.While liquid water is prevented from passing through the membrane into the interior of the sampler.

Each sampler contains a two packets of sorbent material for QA/QC purposes.

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GORE™ Module Analysis

No adsorbent transfer in fieldThermal desorption/GC/MS• VOCs and SVOCs• US EPA Method

8260/8270 modified

For analysis the adsorbent is transferred directly to the thermal desorption tube in the lab.There is minimal sample (adsorbent) handling and exposure to ambient air.

Thermal desorption is used rather than solvent extraction be cause it allows for lower detection capability.

Following the desorption step, the sample is analyzed using Gas Chromatography and Mass Spectroscopy detection (GC/MS) (US EPA Method 8260/8270 modified for thermal desorption).

This sampler can be used for sampling VOCs (including the water solubles) and SVOCs

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GORE™ Module Advantages

Sample small diameter wells and multi-level systems• >0.25 inches• Crooked wells

No minimum sample volume limitationNo need to refrigerate samplesMinimal water disruption - ~10 mls displacementShort sampling period - 15 minutes to 4 hours• Longer-term deployment – sub ppb concentrations

US EPA ETV verified (Einfeld and Koglin, 2000)• http://www.epa.gov/etv/pdfs/vrvs/01_vr_gore.pdf

Like the HydraSleeve™ Sampler, the GORE™ Module can be inserted into crooked wells

There is no need to ship the modules on ice or refrigerate after collection.

Typical sampling times are short range from 15 minutes to four hours.However, the sampling time can be extended to days or months if you need to detect very low concentrations.

This technology was verified by the US EPA in 2000 in their Environmental Technology Verification program. The report can be found at the web site listed in the slide.

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GORE™ Module Limitations

Sole source supplier and laboratory analysisOrganic compounds only • Compound detection limited by vapor pressure

Data reporting• Measured mass (µg)• Concentrations are calculated by GORE based on

Measured mass, sampling rate, time, water temperature, and water pressure

– Reference Section 2.4.5 of ITRC Protocol Document (DSP-5)

W.L GORE is only one supplier and the samples must be sent to the GORE laboratory for analysis.

The technology is limited to organic compounds that have sufficient vapor pressure to partition out of water and diffuse through the membrane.

Section 2.4.5 of the ITRC Protocol Document (DSP-5) contains a detailed summary on how concentration values are calculated.

The sampling rate refers to the uptake of compounds by the GORE™ Module, mass uptake over time. The sampling rate has been quantified (measured) experimentally under controlled conditions. This rate is then corrected to water temperature and water pressure conditions in each well.

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68GORE™ Module – VOC Field StudyMilitary Base, Mid-Atlantic United States

Strong spatial correlation with low-flow samplingGreater sensitivityBetter plume delineation

1,1,2,2-Tetrachloroethane

GORE™ Module data Low-flow sampling data

The contour map on the left illustrates the total mass recovered with the GORE™ Module (not concentration data).The map on the right illustrates the results of low-flow sampling (in ug/L).

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69GORE™ Module – VOC Field StudyDry Cleaner, Southeastern United States

Compared to slow purge and disposable bailerGood correlation

PCE, TCE, cis-1,2-DCE (ug/L)

y = 1.1611xR2=0.982

N=12

0 10000 20000 30000Concentration – GORE™ Module

Con

cent

ratio

n -B

aile

r

C1,2-DCETCEPCELinear

30000

20000

10000

0

Illustrated here are the results of a study conducted at a dry cleaner site in the southeastern US.

Samples collected with a bailer following low-flow purging were compared with samples collected using the GORE™ Module (samples taken first)

Calculated concentrations are shown for the GORE™ Module on the x-axis for PCE and the daughter compounds.The measured concentrations from the bailer sampling are shown on the y-axis.

The correlation between the two datasets is quite good across a range of concentrations.

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GORE™ Module Summary

Accumulation sampler• Passive operation• Compounds partition to vapor, then diffuse to adsorbent

Easy field deployment• Small diameter wells• Short sampling period

Sensitive to low concentrationsCollect samples at a discrete interval in well screenData reported • Mass measured or as concentrations (calculated)

Data comparable with conventional samplingCan only be used for organic compounds

To summarize:The GORE™ Module is an accumulation sampler. The details of the sampler are described in Section 2 of the ITRC Protocol Document (DSP-5).

The module can detect very low concentrations of analytes.Because of this ability, this sampler can provide in some cases more accurate delineation of the groundwater plumes.

Sampler is only able to recover dissolved organic compounds that are able to partition to the vapor phase and diffuse through the membrane and accumulate on the adsorbent.

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71 Overall Summary for Protocols for Use of Five Passive Samplers

Passive Samplers offer• Quantitative data• Cost savings

Use is dependent upon the DQOsTech & Reg GuidanceAcceptanceDiffusion Samplers • RPP & Dialysis

Equilibrated Grab Samplers• Snap Sampler™ &

HydraSleeve™Accumulation Sampler• GORE™ Module

Collect samples at a discrete interval in well screen

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Thank You for Participating

Links to additional resources• http://clu-in.org/conf/itrc/

passsamp/resource.cfm

2nd question and answer session

Links to additional resources: http://clu-in.org/conf/itrc/passsamp/resource.cfm

Your feedback is important – please fill out the form at: http://clu-in.org/conf/itrc/passsamp/

The benefits that ITRC offers to state regulators and technology developers, vendors, and consultants include:Helping regulators build their knowledge base and raise their confidence about new environmental technologiesHelping regulators save time and money when evaluating environmental technologiesGuiding technology developers in the collection of performance data to satisfy the requirements of multiple statesHelping technology vendors avoid the time and expense of conducting duplicative and costly demonstrationsProviding a reliable network among members of the environmental community to focus on innovative environmental technologiesHow you can get involved with ITRC:Join an ITRC Team – with just 10% of your time you can have a positive impact on the regulatory process and acceptance of innovative technologies and approachesSponsor ITRC’s technical team and other activitiesBe an official state member by appointing a POC (State Point of Contact) to the State Engagement TeamUse ITRC products and attend training coursesSubmit proposals for new technical teams and projects

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