groundwater sampling Archives - EON Products, Inc.

Groundwater Remediation, Passive Groundwater Sampling, Uncategorized, Water Quality

Collecting Groundwater Samples for PFAS Analysis

Bench and field scale studies indicate that dual membrane passive diffusion bags may be a viable and readily available technology for the collection of groundwater samples of per- and polyfluoroalkyl substances.

The Military Engineer Magazine – By Paul Caprio, PG, S.SAME, Erica Thiekman, M.SAME, and Steven Gragert, CHMM

Due to the historical use of aqueous film forming foam with per- and polyfluoroalkyl substances (PFAS), the Department of Defense (DOD) is currently managing a growing number of sites with known or suspected contamination. Groundwater monitoring for PFAS at these locations is conducted using low-flow well sampling procedures, which employ portable pumps, dedicated tubing, real-time water quality measurements, and may require management of investigation-derived waste.

A research team comprising EA Engineering, Science and Technology Inc. PBC, EON Products Inc., and the Omaha District of the U.S. Army Corps of Engineers evaluated the effectiveness of Dual Membrane Passive Diffusion Bag (DMPDB) technology to collect representative groundwater samples for PFAS analysis. Although passive sampling groundwater technologies have been routinely used for more than 20 years at DOD sites for volatile organic compounds, metals, and inorganic analysis, their reliability for monitoring PFAS in groundwater is the subject of ongoing bench scale and field study research.

CURRENT ALTERNATIVES

There are several passive samplers under evaluation for the collection of groundwater samples for PFAS analysis. These include grab samplers for instantaneous recovery; sorption-type samplers where contaminant mass accumulated over a known duration is used to calculate concentration, and equilibrium-type samplers that reach and maintain equilibrium with the sampled medium.

Traditional PDBs consist of semi-permeable membrane bags filled with deionized water. The bags are placed in the saturated screen intervals of groundwater monitoring wells where molecules diffuse across the membrane pores into the smaller until the concentration equalizes between the groundwater and the outside of the sampler. The single polyethylene diffusive membrane utilized in traditional PDBs is permeable to non-polar volatile organic compounds but not to other common analytes.

It has been well documented that the collection of groundwater samples using passive samplers results in both significant cost and time savings relative to other common sampling techniques, due to lower equipment and labor costs. Passive samplers also lower the chance of cross-contamination, allow for depth-specific profiling and generate less investigation-derived waste. This is of particular concern at PFAS sites where treatment and disposal techniques are still evolving. Additionally, several passive sampling technologies yield very low turbidity sample aliquots, which is vital for reduced matric interference during laboratory analysis. Equilibrium-type samplers allow for sample aliquots to be collected directly in the field and prepared using conventional methods. Conversely, sorptive samplers require additional preparatory work to extract target chemicals from the sorptive media prior to analysis.

TECHNOLOGY DESCRIPTION

DMPDBs apply the same concept as PDBs, but utilize two membranes with different diffusion capabilities to expand the analyte list beyond volatile organic compounds. None of the DMPDB materials are considered to be sources of PFAS. The upper membrane, made of polyamide, has larger pores and is hydrophilic; this facilitates diffusion of polar and larger molecules into the sampler, such as metals, cations, anions, and 1,4-dioxane. PFAS, which consists of carbon chains bonded to fluorine atoms with hydrophilic polar functional groups, are both polar and relatively large compared to volatile organic compounds. They pass through the upper membrane of the DMPDBs. The lower membrane, made of high-density polyethylene, has smaller pores and is hydrophobic. It is permeable to relatively small volatile organic compound molecules.

This lower membrane also prevents water from escaping the smaller, serving as a sample reservoir. Suspension tethers are typically made of polypropylene=braided cord manufactured without PFAS and are dedicated to each well.

BENCH SCALE TESTING

In 2017, a bench scale study evaluated the ability of DMPDBs to collect representative PFAS samples in a controlled environment using a polyvinyl chloride test chamber filled with a known volume of PFAS-free water that was spied with eight PFAS — including long-, medium-, and short-chain substances — at target concentrations of 20-30 ng/L. The liquid was mixed and allowed to stabilize for six days. The first test consisted of nine samplers that were allowed to equilibrate with the tank water for 21 days (three DMPDBs) and 41 days (six DMPDBs) prior to sample collection.

A second test was performed for tank concentrations between 1- ng/L and 10-ng/L and a residence time of 21 days. A pair of control samples were taken from the chamber port during each retrieval event. All the samples were analyzed for the eight PFAS using a modified Method 537.

FIELD STUDY METHODS

Side-by-side samples were collected from 10 wells with known PFAS impacts at a DOD facility using PMPDB and low-flow purge techniques. DMPDBs were filled with PFAS-free primer water, installed in one mobilization, and allowed to equilibrate for 21 days. This duration was applied based on the shorter of the two durations used during bench scale tests (21 days and 41 days), where comparable results were observed. There is no maximum known timeframe for retrieval. A sample of the water used to fill the PMPDBs was collected to confirm it was PFAS-free. A single DMPDB was placed in the center of the screen of each well, and two DMPDBs were deployed in tandem in two of the wells.

After 21 days, the DMPDBs were retrieved from each well and sampled. High-density polyethylene tubing and a submersible pump were then deployed to purge and collect another sample using low-flow procedures. Flow flow, DMPDB, and field quality control samples were packed in ice and shipped to a DOD-accredited analytical laboratory for analysis in accordance with Quality Systems Manual Version 5.3 Table B-15 for 24 PFAS.

DATA AND RESULTS

Some apparent stratification was observed in one of the two wells with tandem DMPDBs. As a result, only the lower DMPDBs were used for comparison to low flow samples for consistency. PFAS were reported in 126 pairs of the 240 pairs of results that were analyzed. All pairs with detections were used for compassion on a 1:1 regression plot, with low-flow results on the x-axis and DMPDB results on the y-axis. However, only pairs with results greater than five times the reporting detection limits were used for relative percent difference analysis to eliminate artificially high results produced from comparing low values.

This process also was used to analyze results from a set of low-flow field duplicate samples collected during the field event for comparison, and for field study results less than 200 ng/L, which are more representative of values within the range of existing screening levels.

REAL-WORLD APPLICATION

DMPDB PFAS results correlated well with the bench scale and field study samples. They were comparable to the low flow field duplicate sample, and did not produce any results that affected comparisons to screening levels. Additionally, DMPDBs appeared to produce consistent results for both long- and short-chain substances, indicating that it may be suitable for PFAS sampling in future projects — although it may be better suited for sites with regular sapling events to eliminate the need for two mobilizations.

The cost benefits of DMPDBs were not evaluated in this effort. However, studies performed by both the Interstate Technology & Regulatory Council in 2004 and DOD’s Strategic Environmental Research & Development Program/Environmental Security Technology Certification Program in 2014 indicated that the cost savings associated with switching from low flow to equilibrium passive samplers can be expected in the range of 40 to 70 percent for long-term monitoring programs.

This article was written by Paul Caprio, PG, S.SAME, Erica Thiekman, M.SAME, and Steven Gragert, CHMM, and published by The Military Engineer magazine. To read the original article, click here.

Passive Groundwater Sampling, PFAS

What are PFAS Chemicals?

Per- and polyfluoroalkyl substances (PFAS) are synthetic chemicals that are manufactured and utilized in a variety of industries worldwide. Despite the commonality of these man-made substances including PFOA, PFOS, and GenX, PFAS have been shown to have a correlation with negative health effects.

The Risks Associated with PFAS - EON Products, Inc.

Where can you find it?

PFAS commonly finds its way into surface water, groundwater and drinking water supply from sources including landfills, wastewater treatment facilities, and even firefighter training area where PFAS in fire-fighting foams soaks into the soil and is carried away by runoff from rain. Once in the soil and water, this substance accumulates and finds its way into living organisms, such as plants and fish, and then up the food chain to humans. Food is often grown in soil that contain the substance, and prepared foods are often packaged in PFAS-coated wrappers. Many common household products contain the substance as well, including but not limited to: paint, polishes, waxes, cleaning products, and water-repellant fabrics.

There is an extensive list of consumer products that contain these chemicals, including cookware, pizza boxes, stain repellants, and clothing.

What are the effects of PFAS?

Animals and the human body are not equipped to break down PFAS, which means these chemicals can build up in organs and tissues. Animals that have been exposed to PFAS exhibit changes in liver, thyroid, and pancreatic functions. Increased cholesterol levels are one of the leading effects of PFAS exposure in humans. Other consequences can include low infant birth weights, depreciated immune systems, thyroid hormone disruption from exposure to PFOS, and even can cancer from PFOA.

How can you reduce PFAS exposure?

If you live in or near an area impacted by PFAS contaminants, you can check with local water boards to see if there are any advisories in effect for drinking water. the Interstate Technology Regulatory Commission (ITRC) is an organization of technical professional that have published Fact Sheets and informational documents on PFAS and other compounds that affect human health.

Additionally, the United States Environmental Protection Agency (EPA) has made significant progress under the PFAS Action Plan to help states and local communities address the substance and its effects, and protect public health.

EON’s solution

Much of the drinking water and agricultural irrigation in the U.S. comes from groundwater. Monitoring groundwater for PFAS and taking action to reduce the impact of contaminated groundwater is of critical importance to preventing its spread throughout the food chain. EON Products manufactures and provides passive groundwater samplers to environmental monitoring consultants, who then use these devices to accurately sample virtually any compound in the groundwater including; VOCs, Metals, Semi-Volatiles, 1,4 Dioxane, and Per and Polyfluoroalkyl Substances. Users experience all the ease of use and cost saving benefits of passive diffusion sampling plus verified performance on sample results for the low concentrations, to less than 2 parts per trillion, of some of the more commonly detected PFAS in the environment.

Our PDBs are made from materials that do not contain PFAS and have been listed as acceptable materials for sampling this substance. And, because they are immersed in the aquifer water for an extended time, concentrations in the groundwater are able to equilibrate with the PDB sampler materials before the sampler is removed, virtually eliminating the potential for low-bias caused by absorption to the sampler materials.

For more information on our passive groundwater samplers for PFAS and other compounds of emerging concern, contact the experts at EON today.

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Groundwater Remediation

Groundwater Remediation for Environmental Safety

For farmers, landowners, businesses and local governments, groundwater is an essential resource. If local groundwater is not properly protected and managed, contamination can quickly become a common environmental problem that will reduce or eliminate the ability to use the resource and require remediation to restore its value.

Groundwater remediation is the process of managing and reversing the effects of contamination in the underground water supply that may be caused by industrial, agricultural, or consumer activities. Contaminants may include oil, chemical solvents, fertilizers, heavy metals, and other potentially dangerous substances. Often released into the environment by runoff or discharge into streams, lakes, rivers and oceans, the contaminants can find their way into the food chain and cause long-term contamination of wildlife, farm products, and ecosystems. If ingested, many of these pollutants can cause illness or be fatal to human health.

Although groundwater quality is highly influenced by geologic processes, human activity is a strong factor as well. Proper storage and disposal of potential pollutants, proper land use management, runoff management, and protection measures around wellheads and sinkholes can help protect water quality and prevent contamination.

Because groundwater contamination can become both an expensive and safety issue, it can be considered a legal risk within many industries. Therefore, it is important to utilize advanced remediation technologies to properly manage and solve contamination problems wherever they exist.

When it comes to achieving basic groundwater remediation, EON Products understands the importance of high quality and easy-to-use tools. Our remediation products are designed to effectively remove dangerous materials, including hydrocarbon contaminants, from groundwater, while minimizing cost and wastewater disposal to ensure project success for the end user. Our products include passive and active groundwater remediation skimmers, spill kits and absorbent materials, DNAPL and LNAPL recovery systems and sparging systems.

With our passive skimmers, absorbent socks and pneumatically-operated pumping systems, the user can collect and eliminate light non-aqueous phase liquids (LNAPLs), such as hydrocarbon containments, resulting from tank leaks, dry cleaners, spills, or other discharge events.

For more information on our groundwater remediation products, contact our team today.

Passive Groundwater Sampling

The Advantages of Passive Groundwater Sampling

Since passive groundwater sampling was introduced over 20 years ago, the reliable, cost-effective sampling collecting alternative to groundwater purging has gained wide acceptance by environmental regulators and consultants.

This form of groundwater sampling allows the collection of a representative sample from a discrete position within the well screen without active groundwater transport induced by pumping or other techniques. Under natural gradient conditions, samples collected within the well screen, without purging, can be considered representative of the surrounding formation groundwater at a given time and depth interval.

Common advantages of passive sampling include that the sampling product:

is relatively easy to use;
can be deployed in most wells;
can sample discrete intervals in a well;
is practical for use where access is difficult;
can be deployed in series to provide a contaminant profile;
has no depth limitations;
reduces field sampling variability resulting in highly reproducible data;
allows rapid field sample collection;
decreases field labor costs for long-term monitoring;
minimizes sampling derived waste;
minimizes purge water generation and associated disposal costs; and
is an environmental-friendly, sustainable practice.

Passive diffusion samplers have evolved to meet growing groundwater sampling needs and are used to sample a wide range of analytes including VOCs, metals, ions, and compounds of emerging concern, such as 1,4 dioxane and PFAS. Field case studies demonstrate that these products produce accurate sample concentrations and provide significant cost savings compared to low-flow and volume purge.

Since 1998, EON Products has provided the widest selection of low-cost, easy to use and reliable passive groundwater sampling techniques. Our Equilibrator™ Passive Diffusion Sampler and the HydraSleeve™ passive grab sampler are the most-used passive groundwater samplers in the world, supporting hundreds of thousands of successful sampling events. EON’s constant innovation and industry engagement continue to produce new and more versatile passive groundwater samplers to meet growing environmental and budgetary needs.

If you want to learn more about passive groundwater sampling or our range of sampling products, contact EON today.