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Welcome – Thanks for joining us.
ITRC’s Internet-based Training Program
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)
Sponsored by: Interstate Technology and Regulatory Council (www.itrcweb.org)
Hosted by: US EPA Clean Up Information Network (www.cluin.org)
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.org
Training Co-Sponsored by: US EPA Technology Innovation and Field Services Division (TIFSD) (www.cluin.org)
ITRC Training Program: [email protected]; Phone: 402-201-2419
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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
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technology or technology provider through ITRC training or publication of guidance
documents or any other ITRC document.
Copyright 2010 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.
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endorsing any of them.
•Finally, if you want to use ITRC information, you should ask our permission.
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ITRC (www.itrcweb.org) – Shaping the
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The Interstate Technology and Regulatory Council (ITRC) is a state-led coalition of
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ITRC Course Topics Planned for 2010 –
More information at www.itrcweb.org
Popular courses from 2009
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New in 2010
X Decision Framework
Decontamination and Decommissioning of
for Applying
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to Metals and
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Protocol for Use of Five Passive Samplers
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More details and schedules are available from www.itrcweb.org under “Internet-based
Training” and “Classroom Training.”
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Meet the ITRC Instructors
Kimberly McEvoy
New Jersey Department of Environmental Protection
Trenton, New Jersey
609-530-8705
[email protected]
Hugh Rieck
US Army Corps of Engineers
Omaha, Nebraska
402-697-2660
[email protected]
Louise Parker
U.S. Army Engineer Research and
Development Center
Hanover, New Hampshire
603-646-4393
[email protected]
Kimberly McEvoy 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 of
sampling 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…
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What is passive sampling?
What passive samplers offer
• Quantitative data
• Cost savings (40-70%)
How passive samplers
reflect aquifer conditions
Technical and regulatory
guidance
Acceptance of passive
sampling
Classes 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 sampling
Save 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
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Diffusion Sampler Team formed in 2000
Initial goal
• Develop guidance on polyethylene diffusion bags (PDBs) for
collection of volatile organic compounds (VOCs) in groundwater
ƒ 1st passive sampling device - diffusion type sampler (DSP-3)
ƒ Limited in analyte capabilities
ƒ Increased interest and development of passive devices
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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 reexamine 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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What Does a Purge Sample
Represent?
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Active transport of water induced either by pumping or
hand-purging
Often draws water from above and below as well as
adjacent to the screened interval/open borehole
Flow-weighted average
• Based on indicator parameter stabilization or evacuation of
the sampling system (i.e., volume purge)
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• 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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What Does a Passive Sample
Represent?
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No active transport of water induced by pumping
or purging
Samples are collected from a specific depth
Rely on sampling device and well water being in
ambient equilibrium with the formation water
during deployment period
Reduce disturbance to the well and aquifer
typically caused by bailing or over-pumping
Reduce 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
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Highly reproducible data
Provides low turbidity samples
Disposable/dedicated - no decontamination between
wells
Decrease costs
• Field labor ↓
ƒ Rapid field deployment and collection
ƒ Leave in quarterly
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• Little or no disposal cost (no purge-water)
Samples discrete intervals
• Vertical contaminant profiling
• Monitor zone of highest contaminant influx
Easy to use – minimal equipment needs
No depth limit
“Green” sampling method
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
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May have volume/analyte limitations
Contaminant stratification requires consideration
before deploying
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
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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
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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%)
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Technology Overview of Passive Sampler Technologies (March 2006, DSP-4)
• Main application was groundwater sampling
• Summarized 12 passive sampling technologies
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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)
http://www.itrcweb.org/teamresources_1.asp
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.cluin.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
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Diffusion Samplers: analytes
reach and maintain equilibrium via
diffusion through membrane
• Regenerated-Cellulose Dialysis
Membrane (Dialysis) Sampler
• Rigid Porous Polyethylene (RPP)
Sampler
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Equilibrated 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
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Relies on flow through in the well
screen
• Screened zone is in active exchange
with formation water
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Water 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 flow vertically, either upward or downward, through
the well screen to zones of lower hydraulic head (more specifically, toward zones of a lower
pressure head component of total 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 LowFlow 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
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Device suitable for analytes of interest
Sample volume
• i.e., QA/QC and duplicates
• Appendix A: Minimum Volumes
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Deployment period
• Device and site specific
ƒ Well restabilization
ƒ Sampler equilibration
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Deployment depth
• Should not be arbitrary
ƒ 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.”
16
17
Contaminant Stratification
X
Stratification is well-specific
X
Majority of wells are not
stratified
X
Contaminant stratification
in an aquifer
vs.
in the well
You can have:
Stratified or unstratified contaminant distributions in aquifers
Contaminant 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)
17
18
Contaminant Stratification (continued)
Stratification in a well
No stratification
140
20 Low-flow
sample
30
PDB
samples
35
Water Table
160
40
170
45
180
50
0
PDB Samples
Purge Sample
150
25
Depth (feet)
Depth (feet below top of casing)
15
0
20 40 60
Toluene (µg/L)
400
800
1200
Total BTEX Concentration (mg/L)
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.
18
19
Contaminant Distribution
X
Multiple samplers deployed through screened or open interval
X
Vertical flow profiling, depending data quality objectives (DQOs),
determines primary input/exit of groundwater flow
• Can represent contaminant concentrations over water column
X
X
• 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
ƒ 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.
19
20
Data Quality Objectives (DQOs)
X
X
Prior to implementation, all parties should agree
on DQOs
For 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
X
X
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 comparison
High-temporal concentration variability: side-by-side comparison may be more useful
20
21
Data Quality Objectives (DQOs)
(continued)
X
DQOs define
• Sampling goal
• Target analytes
• Hydrologic concerns
Pumping moves water toward
intake from the induced flow
field in proportion to
hydraulic conductivity
Every groundwater sampling technique
characterizes contamination differently!
X
X
Pumping methods
• Draw groundwater into the well screen
from an undefined area
• Example: 3-volume purge and low flow
Passive methods
• Sample depth-specific intervals in well
• Groundwater moves through the well
screen under ambient flow conditions
Pump
Intake
A representative DQO process, as it is used by the Department of Energy (DOE), can be found at
http://dqo.pnl.gov/why.htm
OLD SPEAKING POINT:
When replacing one type of sampling method with another the Team finds that a comparison study
may be required for approval of the new method. The Team has found that side by side tests or
historical sampling results are the most common ways of comparing techniques. The Team has
found that 80 to 90 percent of these comparison studies show similar (I.e. compare well) or the
same results.
ADDED:
One comparison study conducted at the former McClellan Air Force Base will be referred to as the
McClellan Study in upcoming slides of some of the passive sampling technologies. To date, this is
the only large-scale federally funded study comparing passive samplers, volume purge sampling,
and low-flow purge and sampling. If interested in this report, we encourage you to also look at the
sampling protocols to understand the reported results.
21
22
Regulatory Perspective
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)
X
X
X
X
No regulatory or statutory prohibitions
to using passives samplers
“De facto” acceptance of passive
samplers in 50 states and worldwide
New Jersey Department of
Environmental Protection guidance on
polyethylene diffusion bags (PDBs)
(2005)
Regulatory agencies use ITRC
Polyethylene Diffusion Bag (PDB)
guidance for state guidance
Passive
samplers
have been
used
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.”
22
23
In Summary
X
X
X
X
Passive samples collect analytes that come in
contact with the sampler under ambient flow
Value 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
ƒ 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 well
These methods are how the team recommends a side-by-side comparison study; however, these
methods minimized temporal variability but we can never eliminate spatial variability.
Only about 20% of the comparisons are not 1:1
23
24
Questions and Answers
Covered so far
X Introduction to passive (nopurge) sampling
X Advantages/limitations
X General considerations
when using passive
samplers
X Regulatory perspectives
Next – technical aspects for five
passive samplers
X Diffusion Samplers: analytes
reach and maintain equilibrium via
diffusion through membrane
1. Regenerated-Cellulose Dialysis
Membrane (Dialysis) Sampler
2. Rigid Porous Polyethylene (RPP)
Sampler
X
Now
Questions and answers
X
X
Equilibrated Grab Samplers:
collect a whole-water sample
instantaneously
3. Snap Sampler™
4. HydraSleeve™ Sampler
Accumulation Sampler: rely on
diffusion and sorption to
accumulate analytes in sampler
5. 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.
24
25
Diffusion Samplers
X
Diffusion Samplers: analytes
reach and maintain equilibrium via
diffusion through membrane
1. Regenerated-Cellulose Dialysis
Membrane (Dialysis) Sampler
2. Rigid Porous Polyethylene (RPP)
Sampler
X
X
Equilibrated Grab Samplers:
collect a whole-water sample
instantaneously
3. Snap Sampler™
4. HydraSleeve™ Sampler
Accumulation Sampler: rely on
diffusion and sorption to
accumulate analytes in sampler
5. GORE™ Module
Diffusion samplers typically are filled initially with deionized (or distilled) water. Analytes from the
well water diffuse over time through the sampler membrane and into the sampler, so that
concentrations inside the samplers approach equilibrium with those present in the well water.
Equilibrium diffusion samplers using a polyethylene membrane, the polyethylene diffusion bag (PDB)
sampler, have been previously tested and rapidly increased in use over the last 6 years or so. But,
because diffusion samplers using a polyethylene membrane 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).
The two types of diffusion-based samplers discussed in this training are the cellulose membrane
diffusion sampler, and the rigid porous polyethylene sampler. Both can sample a wide variety of
analyte types.
Because diffusion samplers are depth-specific, they can reflect only the analyte concentrations in the
well water to which they are exposed under ambient ground water flow conditions. One of the most
important considerations in interpreting data from passive sampling is having an in-depth
understanding of how a specific well, and the sampling methodology used to sample that well,
represent conditions in the aquifer.
25
26
Diffusion Sampler Basics
The diffusion process is described by Fick’s Law. This simplified general form of Fick’s Law shows
that, given the proper amount of time, dissolved chemical concentrations on either side of a semipermeable membrane will come to equilibrium. As portrayed on the left, the diffusion sampler is
initially filled with de-ionized water (low concentration). Analytes outside the sampler in the well
water diffuse into the sampler until the concentrations on either side of the membrane are equal.
The concentration gradient across the membrane drives the diffusion; the rate of diffusion diminishes
as the sampler approaches equilibrium. The rate of diffusion also is strongly affected by
temperature; the warmer the water the more quickly equilibrium will be approached. The diffusion
coefficient, D, contains the term for temperature, and also is analyte dependent. In this general form,
the distance term, L, reflects membrane thickness and other membrane properties affecting the time
required for equilibration.
It is important to note that this process is reversible. If analyte concentrations in the well water
decrease, analytes will diffuse back out of the sampler over time toward a new equilibrium; the
sampler will follow, with some time lag, changes in analyte concentrations in the well water.
However, this reversibility can be of particular concern when the samplers are retrieved and volatile
constituents (VOCs) are analytes of interest. VOCs begin to diffuse out of the sampler as soon as
the sampler is exposed to air, or any medium having lower concentration of VOC analytes. Exposure
to heat and wind will accelerate VOC loss. The sample must be transferred from the diffusion
sampler and sealed in the laboratory container (VOA vial) promptly upon retrieval. Depending on
specific conditions, measurable VOC loss can occur within a few minutes.
Different membrane materials are used for their different diffusion properties, but the principles
remains the same.
26
27
Diffusion Sampler Advantages
X
X
X
X
Groundwater sampling time in the field is decreased –
no pumping needed
Eliminates purge water and disposal costs
Excludes turbidity from groundwater samples – no filtering
needed
Disposable – no cleaning or cross-contamination
Regenerated Cellulose
Dialysis 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 recover a diffusion sampler and deploy another for the next
sampling event is much shorter than the time it takes to pump and stabilize a well prior to low-flow sample
collection. (3x-6x shorter). This significant saving of time for field personnel substantially lowers field
sampling costs.
- The amount of water removed from the well is minimized. Most, if not all of the water recovered by a
diffusion sampler is transferred into the sample containers for shipment to the laboratory.
- Diffusion sampler membranes have small pore sizes that eliminate or greatly reduce turbidity. The
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.
27
28
Regenerated-Cellulose Dialysis
Membrane Sampler Basics
X
X
X
X
X
X
X
Referred to as the “Dialysis Sampler”
Regenerated-cellulose dialysis
membrane
• Filled with deionized water
• Hydrophilic membrane
Currently must be constructed
Membrane 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 Angstroms
Developed 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.” It was first developed about 6 years ago by researchers at the US Geological
Survey. It uses a tubular membrane made of regenerated cellulose dialysis material, filled with
deionized water, and suspended in the water column in the open interval of a well. After a sufficient
equilibration period, the sampler is removed and the water transferred to appropriate containers for
transport to the laboratory.
Because the dialysis membrane is hydrophilic, water molecules, ions, and dissolved compounds
pass through the membrane. [As opposed to the polyethylene membranes which are hydrophobic so
water and ions can not pass through them.] The cellulose membrane material has an average pore
size of about 18 Angstroms (0.0018 microns), and thus is a very effective particulate filter excluding
even colloidal size clay particles. Thus, turbidity is minimal and the sample will contain only truly
dissolved concentrations, and not analytes adsorbed onto suspended material.
Currently, dialysis samplers are not commercially available so they must be constructed by the user
prior to deployment. The cellulose membrane material comes as roles of lay-flat in tubing, available
in different sizes – 1.25-inch diameter which fits inside a 2-inch diameter well, and 2.5-inch diameter
which fits inside a 4-inch diameter. A 1.25-inch diameter by 2 ft long sampler contains ~500 ml of
sample, and a 2-foot long 2.5-inch diameter sampler contains ~2 liters. The material has a sulfidebased preservative which must be washed off. Once wet, the samplers should be kept wet
(submerged) until deployment to avoid drying and cracking of the membrane. Construction of a
sampler typically takes about 20 minutes, but can differ based on specific configuration (fittings,
accessories, etc.). Samplers can be slipped into nylon mesh sleeves (as pictured) to protect the
membrane from abrasion or tearing during placement into and retrieval from the well. The mesh also
allows convenient and secure attachment to the deployment line using plastic “zip” ties.
28
29
Dialysis Equilibration Times
X
X
Determined in laboratory in bench-scale tests
95% 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
As with all diffusion samplers, once deployed in a well, dialysis samplers must remain completely
submerged for the entire deployment period, and be allowed to equilibrate for the appropriate amount
of time for the chemicals of interest.
The equilibration times shown here for general categories of analytes were determined by USGS and
US Army researchers in periodically stirred batch tests in the lab. A more detailed list of analytes
tested in the laboratory is given in Table 5-2 of the ITRC Protocol Document (DSP-5).
Most of the common analytes that have been tested come to equilibrium in the dialysis samplers
within 1 to 14 days. Only mercury, silver, and tin were found to take longer than 14 days. Under field
conditions where groundwater is flowing through the open interval of the well, chemical equilibration
may occur at somewhat different rates due to temperature differences and other considerations, but a
14-day rule-of-thumb for deployment should be enough for most situations.
29
30
Dialysis Sampler Advantages
X
X
X
X
X
Collects inorganic and organic chemical
constituents
Quick equilibration and deployment times –
generally 1-2 weeks
Relatively inexpensive to construct
Excludes turbidity from groundwater samples –
no filtering needed
Sample volume can be up to 2 L
An important characteristic of dialysis samplers is that, unlike PDBs, they can collect both organic
and inorganic constituents. Dialysis samplers are slightly more expensive to construct than PDBs
but are still inexpensive compared to renting or buying pumps and related equipment.
Because of their small pore size, dialysis samplers exclude particulates from the collected
groundwater sample so no field filtering is needed.
The volume collected can easily be adjusted by varying the length and/or diameter of the sampler
when it is constructed. A typical practical limitation might be about 2 liters. Keep in mind that longer
samplers will integrate concentrations over a longer depth interval in the well, and require a longer
water column in the screened interval so that the entire sampler remains completely submerged
during the entire deployment period.
30
31
Dialysis Sampler Limitations
X
X
X
X
Must construct sampler from raw materials
Samplers must be kept wet between construction and
deployment
Membrane can biodegrade within 4-6 weeks
• Not a problem for shorter deployments
• Can maintain integrity for longer periods in very cold water
Samplers lose water volume slowly (<3% per week)
• Not a problem for short deployments
• Internal support for high ionic strength waters is available
Field-ready dialysis samplers are not commercially available and must be constructed.
As previously mentioned, the cellulose material should be thoroughly rinsed in DI water to remove
preservative, and must be kept hydrated between the time they are constructed and the time they are
deployed in a well to prevent drying and cracking.
Regenerated cellulose is a biodegradable material, that is, it is food for some bacteria. The rate of
biodegradation is well-specific, depending on the level of biological activity, which is in turn largely
dependent on temperature. These membranes have been shown to biodegrade in wells in temperate
climates within 4 to 6 weeks, however some recent results have shown that their integrity is
maintained for six months and longer in very cold water. Nonetheless, most analytes tested thus far
equilibrate quickly enough through the dialysis membrane so this limitation should not adversely
affect their usefulness for sampling in most wells.
Because diffusion is a two-way process and the cellulose membrane is permeable to water, not only
are dissolved analytes in the well water diffusing into the sampler, but water molecules are also
diffusing outward in an attempt to dilute the well 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.
31
32
Dialysis Field Comparison Results
1000
1000
Low-Flow Purging
Ethylbenzene
(µg/L) 10
Chloride
(mg/L) 10
LRL
0.1
LRL
1/2 MDL
0.1
10
0.1
1000
10
0.1
1000
1000
1000
Vinyl 10
Chloride
(µg/L)
0.1
From:
Imbrigiotta 0.001
et al. (2007)
0.001
1/2 MDL
LRL
Manganese
(µg/L)
10
LRL
1/2 MDL
0.1
10
1000
1/2 MDL
0.1
0.1
10
1000
Dialysis Sampler
These graphs show examples of field comparison results from a study by Imbrigiotta et al. (ESTCP
final report, 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.
32
33
Dialysis Field Comparison Results
(Dialysis Samplers vs Purging Methods)
X
Parameters with favorable
results
• VOCs
• Cations and anions
• Most trace metals
• Explosive compounds
• Others (silica, ethene,
CO2, CH4, TDS, SC,
DOC)
X
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, 111-TCA, 11-DCA, CM,
Chloroform, MC, DCDFM, 12DBE)
•Most aromatic VOCs (BTEX, Styrene, 124-TMB, 135-TMB, iso-propylbenzene, t-butylbenzene, npropylbenzene, 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 (e.g. RDX, HMX)
•Dissolved gases, ethene, CO2, CH4, and TDS, silica, DOC
The only parameters with questionable field comparison to low-flow results include a few aromatic
VOCs (for which dialysis sampler results did compare favorably to PDBs in side by side tests),
nickel, which was present only below reporting limit concentration, 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 results for various analytes is given in Table 5-3 of the ITRC Protocol
document (DSP-5) available the ITRC website (www.itrcweb.org) under “Guidance Documents”
and “Diffusion Samplers.”
33
34
Dialysis Sampler Summary
X
X
X
X
X
X
X
Collects both organic and inorganic chemical constituents
Do not require filtration of samples
Equilibrate within 1-2 weeks for most constituents
Deployment times 1-2 weeks in most wells
Dialysis 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 collect only the truly 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 well through the dialysis
membrane were mercury, silver, and tin - possibly due to the formation of metal-organic
complexes that either sorb to the membrane or are so large that they don’t diffuse readily through
the pore spaces.
-
The potential for biodegradation should be included if dialysis samplers are to be considered for
deployment periods or equilibration times that might extend longer than four (4) weeks, although
they have been deployed for up to six months in very cold water (ice) without measurable
degradation.
-
Dialysis samplers should not be used if total concentrations are required (concentrations that
must include analytes adsorbed on to colloidal particles that remain suspended by Brownian
motion and are naturally mobile under ambient flow in the aquifer).
-
Sampling for nickel and sulfide needs to be further tested.
34
35
Rigid Porous Polyethylene (RPP)
Samplers
Cap
X
X
X
X
X
Delrin plug
X
Made of rigid, porous polyethylene
Pore sizes 6-15 microns
5 inches long
1.5 inches in diameter
Filled with
deionized
water
Standard size
protective mesh ready for
holds 90-100 mL Indeployment
and packaged
in disposable water-filled
sleeve for shipping
Rigid Porous Polyethylene (RPP) samplers were developed by Don Vroblesky of the USGS, and are commercially
available.
The RPP sampler is constructed from a rigid cylinder of foam-like porous polyethylene having a wall thickness of
about 2 mm. The pore size in the material ranges from about 6 to 15 microns. The outside diameter is
approximately 1.5 inch and the individual samplers are limited to about 5 inches in length. If made longer, the
higher head pressure in the sampler forces the water inside to “leak” out through the pores when not submerged.
The RPP sampler is filled with de-ionized, analyte-free water, capped at one end and a Delrin plug inserted into the
other end. The one pictured on the left is equipped with a second smaller plug. Use of the smaller plug will
minimize potential loss of VOCs by any vacuum that may be created by the plug’s removal when transferring
sampler contents into the laboratory containers.
The picture on the right shows an RPP ready for shipment. The RPP is shipped in a mesh liner for protection
during deployment and retrieval, and for convenient attachment to the deployment line using cable ties (“zip” ties).
RPPs are shipped in a water filled polyethylene bag to ensure that the pores stay water filled. If the pore spaces
become blocked by air bubbles, the aqueous diffusion pathway is interrupted and diffusion of analytes into the
sampler may be greatly reduced or not occur at all.
Water soluble analytes pass through the pores until equilibrium is reached between the water in the sampler and
the water to which the sampler is exposed. In bench studies, equilibrium time ranged from hours to days,
depending on diffusion properties of the specific analyte. The more water soluble the analyte, the quicker the
equilibrium. The general rule of thumb for all diffusion samplers, that they should be deployed not less than 14
days, ensures that most analytes will have equilibrated in an RPP sampler. These samplers can remain deployed
in wells for a quarter, but can be expected to maintain integrity for much longer, though there is little information
regarding longer deployments. Biofouling has been considered as a potential problem, but has not been reported
for any of the long-term (quarterly or longer) for any passive sampling device.
35
36
Select RPP Analytes and Equilibration
Times
Analyte
Equilibration time
(days)
Dissolved gases
14
Perchlorate, chloride, hexavalent chromium,
nitrate, sulfate, soluble iron
14
Methane, ethane, ethene (MEE)
14
Water soluble VOAs (i.e. MTBE, MEK,
Acetone, 1,4-Dioxane)
14
Water soluble SVOCs (i.e. NDMA, phenols)
14
Dissolved metals (priority pollutant list)
Explosives (i.e. HMX, TNB, RDX and TNT)
21 (all except
silver and copper)
21
Please see the tables in Chapter 6 of the Protocol Document (DSP-5) for more detailed equilibration
data. New analytes are being added as field studies continue.
Additional field studies on low-solubility (hydrophobic) VOCs and SVOCs are needed. In laboratory
batch studies in sealed carboys, concentrations of the hydrophobic VOCs and SVOCs were depleted
in the test solution, but were not found in the water in the samplers (see Tables 6.5 and 6.7 in the
Protocol Document (DSP-5). These results are consistent with a conclusion the hydrophobic
analytes were adsorbed onto the sampler itself. It’s thought that with longer equilibration times, and
an effectively unlimited volume of contaminated water moving through the wells screen, that the
sampler and water within it would eventually reach equilibrium, but field studies are needed to
confirm this.
36
37
RPP Advantages
X
X
X
X
Can be used to collect most inorganic and limited
organic analytes
Are commercially available and field-ready
Can be stacked when additional volume needed
Excludes particles larger than the pore space of
the sampler
RPP Samplers have the same general advantages as other passive samplers:
•eliminate purge water collection
•are easily deployed and retrieved
•reduce field sampling costs significantly
•may not be a substitute for field filtering using a standard 0.45 micron filter.
37
38
RPP Limitations
X
X
X
X
X
Must be stored and shipped fully immersed in
deionized water
Have not been tested for all analytes
Multiple samplers are needed to obtain sufficient
volume for multiple Analyte types and/or QA/QC
Requires advanced analytical techniques to
analyze for SVOCs
Equilibrium times for less water soluble VOCs
and SVOCs are not currently known
To prevent air from entering and blocking the pore spaces of the polyethylene material, field-ready
RPPs are shipped sealed in water-filled pouches.
Wells must be 2 inches or more in diameter to accommodate the diameter of the RPPs.
RPPs provide only 90-100 mL of sample; if additional sample volume is needed, multiple RPPs must
be stacked. As with several of the passive samplers discussed today, it is very important that you
discuss the small sample volume with your laboratory to ensure they are prepared to meet your
measurement quality objectives (method detection limits (MDL), reporting limits (RL), etc. ) with the
limited volume. Ensure that they have equipment that will allow them to use less volume that
typically requested. For instance, the standard minimum volume required for SVOCs by EPA
Method 8270 is 1000 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. The evolving trend toward more flexible performance-based approaches to
environmental measurement that continue to meet project DQOs, is moving away from prescriptive
requirements of the past.
A table giving minimum volumes required to meet standard DQOs for many common analytical
methods is provided as Appendix A of the Protocol Document (DSP-5). The volumes are those
required for a single analysis, without MS/MSD, re-runs, etc.).
It’s not yet known how long it would take for VOCs and SVOCs to equilibrate. However, RPPs are
frequently co-deployed with a polyethylene diffusion bag (PDB) - the RPPs for water-soluble analytes
and the PDB for hydrophobic VOCs. For example, the combination of passive devices can monitor
1,4-dioxane and 1,1,1-TCA concurrently.
38
39
McClellan AFB Multi-analyte,
Multi-sampler Study (Parsons 2005)
RPPs Sample Concentration (µg/L)
100000
10000
1000
100
Metals:
1,4-Dioxane:
Anions:
Hex Cr:
VOCs:
10
1
For All Data
y = 0.941x
R2 = 0.9764
0.1
0.01
0.001
0.001
0.01
0.1
1
10
100
1000
10000
100000
Low-Flow Purge Sample Concentration (µg/L)
This study at the former McClellan AFB, California, compared 4 diffusion-based sampling devices
and 2 equilibrated grab samplers against low-flow and conventional 3-volume well purging sampling.
This graph depicts results from RPP samplers compared to low-flow pumped 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
It is important to remember that the different purging methods and passive sampling may sample the
well somewhat differently, depending on well-specific hydrologic characteristics.
As mentioned before, 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 work well
for 1,4-dioxane. The next two slides illustrate side-by-side tests for 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.
39
40
RPP Representative Field Study for
1,4-Dioxane at a North Carolina Site
0.25
RPP (mg/L)
0.2
R2 = 0.9224
y = 0.852x
n=9
0.15
0.1
0.05
0
0
0.05
0.1
0.15
0.2
0.25
Low Flow (mg/L)
Each point on the plot represents a singleconstituent data pair of each sampling method.
This correlation plot depicts the low-concentration results from paired samples collected from multiple
wells by RPP and low-flow methods.
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.
The next page depicts the results from all wells, including V-23.
40
41
RPP Representative Field Study for
1,4-Dioxane at a North Carolina Site
3
RPP (mg/L)
2.5
2
1.5
R2 = 0.999
y=1.073x
n=10
1
0.5
0
0
0.5
1
1.5
2
2.5
3
Low Flow (mg/L)
Each point on the plot represents a singleconstituent data pair of each sampling method.
Including the data from V-23 well gives an R2 of 0.999 and y=1.073x, but the scale of this plot makes
the lower concentrations data points difficult to distinguish.
RPPs are now deployed at this site on an on-going basis. This study is described in the Protocol
document (DSP-5) Section 6.5.2 and Table 6.10.
41
42
RPP Summary
X
Can be used to sample for
• Most inorganics
• Water soluble VOCs and SVOCs
X
X
X
X
It’s not currently known if they can be used for
water-insoluble VOCs and SVOCs
Can be used in deep wells
Can be used in conjunction with PDBs
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.
Depth limitations have not been encountered for any of the passive sampling devices.
42
43
Diffusion Sampler Summary
Regenerated Cellulose
Dialysis Membrane
X
X
X
X
X
X
X
Rigid Porous
Polyethylene (RPP)
RPP and Dialysis Membrane samplers can be used for VOCs, SVOCs,
metals, anions, and cations
Minimum deployment time for RPP and Dialysis sampler is ~2 weeks
Compare well with conventional methods
Collect samples at a discrete interval in well screen
RPP sampler can be used for quarterly or longer deployments
Major limitation of RPP sampler is sample volume
Major limitation of Dialysis sampler is that it undergoes biodegradation
*RPP and Dialysis Membrane Samplers are diffusion samplers that provide the important advantages
of passive sampling, and can be used for a much broader range of analytes than the Polyethylene
Diffusion Bag (PDB) sampler.
43
44
Equilibrated Grab Samplers
X
Diffusion Samplers: analytes
reach and maintain equilibrium via
diffusion through membrane
1. Regenerated-Cellulose Dialysis
Membrane (Dialysis) Sampler
2. Rigid Porous Polyethylene (RPP)
Sampler
X
X
Equilibrated Grab Samplers:
collect a whole-water sample
instantaneously
3. Snap Sampler™
4. HydraSleeve™ Sampler
Accumulation Sampler: rely on
diffusion and sorption to
accumulate analytes in sampler
5. GORE™ Module
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.
44
45
Equilibrated Grab Samplers
X
X
X
X
X
Collects sample from discrete
interval in well screen
Collect “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 water
Technologies
HydraSleeve™
• Snap Sampler™
Sampler
• HydraSleeve™ Sampler
Snap Sampler™
Because these samplers do not rely on diffusion or sorption, they can collect a sample that is in real
time.
Typically, these samplers are placed in the well, and left for an equilibration period.
After the equilibration period, the sample is collected.
Allowing the well to recover from placing the sampler in the well
you 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.
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.
45
46
Snap SamplerTM Components
X
X
X
X
Sampler body with trigger
mechanism
Bottles
• Have two openings &
spring-activated caps
• 40-mL VOA glass vials
ƒ Fits in 2-inch wells
• 125-mL HDPE bottles
ƒ Fits in 2-inch wells
• 350-mL HDPE bottles
ƒ Fits in 4-inch wells
Trigger line
• Mechanical
• Electronic
• Pneumatic
Docking station
125 mL
40 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.
To deploy the sampler:
Place the bottles in the sampler.
Place the end caps in an open position using the release pins on the sampler.
Attach the trigger line to the sampler and then use the trigger line to lower the device into the well.
46
47
Snap SamplerTM – Collecting a Sample
X
X
X
X
X
Sample bottles deployed & remain
in open position
Equilibration period
• Minimum of 1 to 2 weeks
• Can be used for quarterly,
semi-annual, or annual
sampling
Pull handle on trigger line to close
bottle (i.e., collect sample)
Samples sealed in situ
No sample transfer required at the
surface
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.
Samples can be sent to the laboratory in the same bottle the sample was collected in.
Or they can be transferred to other sample bottles.
E.g., contents of 125-mL sample bottle could be poured into two 50-mL sample bottles, one
for anions and one for metals
The 40 ml VOA vials are compatible with common autosampler equipment.
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).
47
48
Snap SamplerTM Advantages
X
X
No analyte restrictions
Reduced sampling variability
• Minimal agitation of well
during sampling
ƒ Collect samples with
ambient turbidity
• Bottles remain sealed under
in-situ conditions
• No sample transfer
ƒ No exposure to weather,
surface contamination,
etc.
ƒ Some studies have shown
better recovery 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.
48
49
Snap SamplerTM Limitations
X
Sample Volume
• Multiple bottles are needed to obtain volume for
multiple analyte types and/or QA/QC
X
Trigger lines are fixed length and thus cannot be
readily moved to other wells
Larger volume can be collected by using large sample bottles (i.e., 350-mL) or by deploying
multiple samplers either on multiple trigger lines or in series on the same trigger line.
The more sample bottles deployed along a trigger line, the longer the interval in well that you
are sampling.
Up to 6 samplers depending on type of trigger mechanism and sampling depth.
49
50
Snap SamplerTM – VOC Field Study
Snap Sampler VOC (ug/L)
10000
1000
100
10
1
0.1
0.1
X
X
1
10
100
1000
Low Flow VOC (ug/L)
10000
Very good correlations
Slightly higher concentration values with
Snap SamplerTM than low-flow
Comparison from Boeing Santa Susanna Field Laboratory in Chatsworth, California.
Zimmerman, Laura, Beth Parker, Amanda Pierce, John Cherry, Sandy Britt, Ramon
Arevena, 2009, Use of Snap Sampler and CSIA in Investigations of TCE Natural Attenuation
in Fractured Sandstone, Proceedings of the Groundwater Resources Association of
California Conference: Groundwater Monitoring: Design, Analysis Communication &
Integration with Decision Making, Orange, California, February 25-26, 2009.
Good correlation (as shown by the high correlation coefficient)
“Y” values (or slope) slightly >1
Indicates Snap Sampler™ yields slightly higher concentrations than 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.
50
51
Snap SamplerTM – Multi-analyte Field
Study
Snap Sampler™ Concentration (µg/L)
100000
10000
Anions
1000
Study at former
McClellan Air
Force Base
(Parsons Inc. 2005)
100
10
VOCs
1,4 Dioxane
1
R2 = 0.99 for all
analyte comparisons
to low flow
0.1
0.01
0.01 0.1
1
10
100
1000 10000 100000
Low-Flow Purge Sample Concentration (µg/L)
Snap Sampler™ also showed excellent correlations with volume-based purge methods.
51
52
Snap Sampler™ Summary
X
X
X
X
X
Sample all analyte types
Volume limited for long
analyte list
Samples are sealed at the
point of collection
No transfer of sample
required
Data correlates well with
standard sampling
methods
More information on the Snap Sampler™ technology can be found in section 4 of the ITRC
Protocol Document (DSP-5).
I have conducted several studies on the Snap Sampler. These tests included both laboratory
and field studies. The laboratory studies compared concentrations of analytes taken from a
standpipe with control samples taken from the standpipe. Analytes included VOCs,
explosives, and a suite of inorganics including metals. Field studies sampled for VOCs,
explosives, and inorganic analytes. The results from these studies can be found in two
reports available at our website (below) and another that will be published by Fall 2010.
http://libweb.wes.army.mil/uhtbin/hyperion/CRREL-TR-09-12.pdf
http://libweb.wes.army.mil/uhtbin/hyperion/CRREL-TR-07-14.pdf
52
53
HydraSleeve™ Components
Sampler sleeve
Reed valve
Discharge tube
Reusable sampler weight
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).
Components
Polyethylene sleeve
Top loading reed style check valve
Reusable stainless steal weight and clip
Discharge tube
HS are designed to fit
2-in wells, (1.5 inches OD)
4-in wells (2.5 inches OD)
Also 1-in wells and ¾-in wells.
To assemble these samplers, simply
•
Unfold
•
Clip weight to bottom
•
Attach tether (line) to top
53
54
HydraSleeve™ Sample Collection
Full
Sample
Interval
Filling
Empty
To deploy the HydraSleeve™, lower the sampler through the water column.
The sampler remains empty as the sampler is lowered through the water column and
during the equilibration period.
To collect a sample,
Pull the HydraSleeve™ upward >1 foot per second
(~the speed a bailer is recovered).
Hydrostatic 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”
The mechanism is much like pulling on a sock.
When the sampler is full, the reed valve closes,
Reed valve remains closed as the sampler is recovered from the well.
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.
Done by puncturing sampler with discharge tube.
Sampling interval within well is ~1.5 times the length of the sampler
54
55
HydraSleeve™ Advantages
X
X
X
X
X
X
Fits in most diameter wells
Can sample all types of analytes
Sample Volume
• 2-inch HS collects 650 mL to 1 L
• 4-inch HS collects 1250 mL to 2 L
Easy to use with minimal training
Can sample
• Very deep wells
• Crooked wells
Can collect low turbidity samples
No associated notes.
55
56
HydraSleeve™ Limitations
X
Sample Volume
• Custom samplers can be fabricated in
a wider diameter and/or longer length
to maximize sample volume for longer
analyte lists
• Work with lab regarding minimum
sample volume
ƒ Using table in Appendix A of the ITRC
Protocol Document, DSP-5
No associated notes.
56
57
HydraSleeve™ – Field Study (1 of 2)
Concentration (ppb)
2-inch diameter well in Northern California (Geomatrix Inc., 2000)
160
140
120
100
80
60
40
20
0
1,1-DCA
1,1-DCE
cis-1,2 DCE
1,1,1-TCA
TCE
Freon 113
HydraSleeve™
Purge/Sample
Good agreement between the VOC concentrations in the purged samples vs. those taken
with the HydraSleeve™ Sampler.
This example was the first well that HydraSleeve was ever deployed in.
57
58
HydraSleeve™ – Field Study (2 of 2)
Former McClellan Air Force Base (Parsons Inc., 2005)
X
X
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
chromium
X
Study Findings
• “The HydraSleeve and Snap SamplerTM produced results
most similar to the higher concentrations obtained by lowflow and 3-well volume purging and sampling methods”
• “Appears to be a technically viable method for monitoring all
of the compounds in the demonstration”
Available on ITRC Diffusion/Passive Sampler team web site:
http://www.itrcweb.org/teamresources_1.asp Technical publications
I also conducted several studies on an earlier version of the HydraSleeve (before the reed valve was
developed). In those tests, we conducted laboratory studies with known concentrations of VOCs,
explosives, pesticides, and metals and a field study that we conducted in one of our wells that was
contaminated with TCE. The results from these studies can be found in a report available at our
website (below) and in a journal paper published in Ground Water Monitoring and Remediation
24(3):111-123.
http://libweb.wes.army.mil/uhtbin/hyperion/CRREL-TR-02-12.pdf
58
59
HydraSleeve™ Sampler Summary
X
X
X
X
X
X
Sample all analyte types
Sample volumes up to 2 L
Can be used in
• Deep wells
• Crooked wells
Comparable results to
conventional pumped methods
Can be left in well for quarterly,
semi-annual, or annual sampling
Disposable sampler
• No decontamination required
Inexpensive to ship (100 samplers will fit in an overnight envelope)
59
60
Equilibrated Grab Samplers Summary
Snap
Sampler™
HydraSleeve™
Sampler
X
X
X
X
X
X
Samples can be analyzed for all analyte types
• Providing there is adequate sample volume
Collect whole water samples in real-time
Can be used for quarterly, semi-annual, or annual sampling
events
Use an equilibration period to reduce sampling biases
Collect samples at a discrete interval in well screen
Compare well with conventional methods
No associated notes.
60
61
Accumulation Samplers
X
Diffusion Samplers: analytes
reach and maintain equilibrium via
diffusion through membrane
1. Regenerated-Cellulose Dialysis
Membrane (Dialysis) Sampler
2. Rigid Porous Polyethylene (RPP)
Sampler
X
X
Equilibrated Grab Samplers:
collect a whole-water sample
instantaneously
3. Snap Sampler™
4. HydraSleeve™ Sampler
Accumulation Sampler: rely on
diffusion and sorption to
accumulate analytes in sampler
5. GORE™ Module
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.
61
62
Accumulation Samplers
X
X
X
Rely on diffusion and sorption
Examples 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://www.itrcweb.org/
Rely on diffusion through a membrane and sorption by some type of sorbent material (either granular
or liquid) housed within the sampler membrane.
This Gore Module is discussed in Section 2 of the ITRC Protocol Document (DSP-5) and is
commercially available.
62
63
GORE™ Module Components
Knot
(secure to
wellhead)
Attachment Line
Loop to
attach line
Tag with unique
serial number
X
GORE™ Module
• Section 2 in ITRC Protocol Document
(DSP-5)
X
X
Attachment Line
Stainless steel weights
Adsorbent
Weight
This sampler is also known as the GORE-SORBER Module
(figure on the left).
The module comes in its own sample vial
Vial and sampler have a unique serial number for identifying sample.
Size of the module is ~ the length and diameter of a soda straw.
Module consists of:
a tube made of GORE-TEX® membrane,
which is a vapor-permeable, waterproof membrane.
& 2 packets of the sorbent material.
To deploy sampler (figures on right):
Attach tether line and weights to bottom.
After collecting sampler,
blot dry with paper towel, place in vial, ship to lab
Sampler can be used for sampling VOCs and SVOCs
63
64
GORE™ Module Sample Collection
X
X
X
X
Dissolved compounds partition to vapor (Henry’s Law)
Diffusion through hydrophobic, vapor-permeable membrane
Adsorption onto media
GORE-TEX® Membrane
Duplicate samples
Vapors pass
through
Liquid
water
remains
outside
Adsorbents
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, diffuse
through the membrane, & are sorbed by the sorbent material.
While liquid water is prevented from passing through the membrane into the interior of the sampler.
64
65
GORE™ Module Analysis
X
X
No adsorbent transfer in
field
Thermal
desorption/GC/MS
• VOCs and SVOCs
• US EPA Method
8260/8270, modified
for thermal desorption
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.
65
66
GORE™ Module Advantages
X
X
X
X
X
X
Sample small diameter wells and multi-level systems
• >0.25 inches
• Crooked wells
No minimum sample volume limitation
No need to refrigerate samples
Minimal water disruption - ~10 mls displacement
Short 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
No associated notes.
66
67
GORE™ Module Limitations
X
X
Sole source supplier and laboratory analysis
Organic compounds only
• Compound detection limited by vapor pressure
X
Data reporting
• Measured mass (µg)
• Concentrations are calculated by GORE based on
ƒ Measured mass, sampling rate, time, water
temperature, and water pressure
– Reference Section 2.4.5 of ITRC Protocol Document
(DSP-5)
W.L GORE
The sampling rate refers to the uptake of compounds by the GORE™ Module, mass uptake over
time.
The sampling rate has been determined experimentally in the lab by Gore.
This rate is then corrected for water temperature and water pressure conditions in each well.
67
68
GORE™ Module – VOC Field Study
Military Base, Mid-Atlantic United States
1,1,2,2-Tetrachloroethane
GORE™ Module data
X
X
Low-flow sampling data
Strong spatial correlation with low-flow sampling
Greater sensitivity & better plume delineation
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).
This data is provided by the manufacturer.
68
69
GORE™ Module – VOC Field Study
Dry Cleaner, Southeastern United States
Concentration - Bailer
PCE, TCE, cis-1,2-DCE (ug/L)
30000
20000
X
C1,2-DCE
TCE
PCE
Linear
10000
0
X
y = 1.1611x
R2=0.982
N=12
0
10000 20000
30000
Concentration – GORE™ Module
Compared to slow purge and disposable bailer
Good correlation
Samples collected with a bailer following low-flow purging
GORE™ Module samples were taken first
Calculated concentrations are shown
This data is provided by the manufacturer.
In the summer 2010, I will be conducting the first of two demonstrations of this technology in
groundwater monitoring wells. The first site we are testing has chlorinated VOCs and the second site
will have hydrocarbon contamination. This work is sponsored by ESTCP and will be available as an
ESTCP report on our website under technical publications.
http://www.crrel.usace.army.mil/library/technicalpublications.html
69
70
GORE™ Module Summary
X
X
X
X
X
X
X
Accumulation sampler
• Passive operation
• Compounds partition to vapor, then diffuse to adsorbent
Easy field deployment
• Small diameter wells
• Short sampling period
Able to detect very low analyte concentrations
Collect samples at a discrete interval in well screen
Data reported
• Mass measured or as concentrations (calculated)
Data comparable with conventional sampling
Can only be used for organic compounds
The details of the sampler are described in Section 2 of the ITRC Protocol Document (DSP-5).
Because sampler can detect very low concentrations of analytes, it can provide in some cases more
accurate delineation of the groundwater plumes.
Sampler is only able to recover dissolved organic compounds with sufficient volatility to partition to
the vapor phase.
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Overall Summary for Protocols for
Use of Five Passive Samplers
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X
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Passive Samplers offer
• Quantitative data
• Cost savings
Use is dependent upon the
DQOs
Tech & Reg Guidance
Acceptance
Diffusion Samplers
• RPP & Dialysis
Equilibrated Grab Samplers
• Snap Sampler™ &
HydraSleeve™
X
Accumulation Sampler
• GORE™ Module
Collect samples at a discrete interval in well screen
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Thank You for Participating
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2nd question and answer break
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Links to additional resources
• http://www.clu-in.org/conf/itrc/passsamp/resource.cfm
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Feedback form – please complete
• http://www.clu-in.org/conf/itrc/passsamp/feedback.cfm
Need confirmation of
your participation
today?
Fill out the feedback
form and check box for
confirmation email.
Links to additional resources:
http://www.clu-in.org/conf/itrc/passsamp/resource.cfm
Your feedback is important – please fill out the form at:
http://www.clu-in.org/conf/itrc/passsamp/feedback.cfm
The benefits that ITRC offers to state regulators and technology developers, vendors,
and consultants include:
9Helping regulators build their knowledge base and raise their confidence about new
environmental technologies
9Helping regulators save time and money when evaluating environmental technologies
9Guiding technology developers in the collection of performance data to satisfy the
requirements of multiple states
9Helping technology vendors avoid the time and expense of conducting duplicative and
costly demonstrations
9Providing a reliable network among members of the environmental community to focus on
innovative environmental technologies
How you can get involved with ITRC:
9Join 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 approaches
9Sponsor ITRC’s technical team and other activities
9Use ITRC products and attend training courses
9Submit proposals for new technical teams and projects
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