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The ABCs of PFOAs

May 22, 2019

PFAS In Our Landfills – What’s Next?

Presented by:

Stephen M. Kline, P.E. Associate Principal

GZA GeoEnvironmental of New York

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1. PFAS Uses and History 2. PFAS Chemistry

3. Fate and Transport

4. Groundwater Sampling

5. Risk Management

6. Take Aways

Outline

Not So Long Ago…

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Uses of PFAS

These things end up in landfills as “Waste”

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History of Select PFAS

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Chemical Molecule

Common Chlorinated Compounds

PFOA – Perfluorooctanoic acid PFOS – Perfluorooctane sulfonic acid • Precursor of PFOA

• Fluorotelomer alcohols

• C-F bond is one of the strongest bonds • nonfluorinated “head” with a polar functional group • carbon-fluorine “tail”

Tail Head C-F Bond

Octane

MCTA • PFAS: Regulation, Research, Risk, Mitigation & Alternatives • May 10, 2018 • Marlboro, Massachusetts

What make PFAS different?

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PFAS (Per- and Poly-) Perfluorinated

Substances

PFCAs

e.g., PFOA

PFSAs

e.g., PFOS

PFPAs Etc.

Polyfluorinated Substances

FTOHs

e.g.,

8:2 FTOH

FTSs

e.g.,

8:2 FTS

FSAs Etc.

Precursors + others

PFOS - Perfluorooctane sulfonic acid

PFOA - Perfluorooctanoic acid

PFHxS - Perfluoro hexane sulfonic acid PFNA - Perfluoronoonanoic acid

PFDA - Perfluorodecanoic acid

Greater than 6,000 compounds 40+ different subcategories

Issues with Precursors

Under the right circumstances, precursors (polyfluorinated) may degrade or transform to the Perfluorinated compounds

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Complex Chemical Reactions Partitioning Mechanisms

PFAS “tail” is hydrophobic and lipophobic drives associations with organic carbon in soil

PFAS “head” are polar and hydrophilic Electrostatic interactions - function of the polar functional group (head)

E.g. soil and groundwater often have negative surface charges that can repel negatively charged heads. This can be in conflict with the tail resulting in partitioning interfaces (soil/water, water/air, water/NAPL)

Sorption & Retardation Increases with perfluoroalkyl tail lengths

Shorter chains are retarded less than the longer chains PFSAs are sorb more strongly than PFCAs of equal chains Branched isomers have less sorption than linear Decreases in pH, increases in cations = greater sorption & retardation

Volatility Vapor pressures are low, water solubility is high (very mobile in groundwater)

limiting partitioning from water to air Stack emissions = atmospheric and particulate transport

MCTA • PFAS: Regulation, Research, Risk, Mitigation & Alternatives • May 10, 2018 • Marlboro, Massachusetts

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Major Pathway: Landfills & WWTP

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CRCCARE, Technical Report 38, March 2017

Fate & Transport - Conceptual Site Model

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Y

X

Singular PFAA

PFAS only; limited

precursors

Comingled and/or

significant precursors

Groundwater C8

C8

C8

<C8

<C8

<<C8

<<C8

Fate & Transport Scenarios

C8

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New York State

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New York State

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New York State

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Cross Contamination - Sampling Issues

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Sampling Issues

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Laboratory Methods Sample Media Type Laboratory Method

Drinking Water EPA Method 537

Soil and Ground Water Modified EPA Method 537

Surface water and Sediments Modified EPA Method 537

Note: EPA has only approved method 537 for drinking water. Individual laboratories have modified the 537 method for other media. Currently, EPA is working on additional Methods.

Source of Contamination Number of Parameters

Coating Sites Typically 12 to 14 compounds

Hazardous Waste Sites 21 compounds

Landfill Sites 21 compounds

DOD/Fire Training Typically 16 to 27 compounds

Laboratory Method

Standard Method EPA Method 537

Uses LC/MS/MS technology and isotropic dilution

TOP Analysis (Total Oxidizable Precursors)

Samples are treated with hydroxyl radical oxidation activated agent with overnight heating converting the masked precursors to their equivalent detectable PFAS compounds. TOP and Standard method combined provide a more complete PFAS assessment

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Risk Management

Assess if, where, and how to sample • Develop a plan of action with QA/QC protocols to reduce the potential for

false positives

Develop a Conceptual Site Model that takes PFAS in mind • Migration pathways • Lithogolic conditions/grain-size • Complex chemical interactions • Complex groundwater quality interactions • Sensitive receptors

Develop a Communication Strategies that anticipates Public Concerns

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When PFAS are detected in a Private Well

Most Important Sensitive Receptors • Public Outreach is Crucial

Can I Drink and Bathe in the Water? • Understanding PFAS Test Results Strategies to Address Detected PFAS • < 10 ppt = no further action • 10 to 70 ppt = retest and consider point of use water filtration to

minimize exposure • > 70 ppt = bottled water, point of use filter, whole house filter,

connect to public water

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PFAS - Take Away

• PFAS are ubiquitous

• Landfills receive PFAS in waste

• Additional investigation warranted to define PFAS pathways from landfills into the environment

• The guidance values are so small that need a good approach prior to sampling

• The regulatory landscape is still evolving: NYSDEC implementing actions to investigate PFAS compounds

• EPA submitted draft recommendations in April 2019

https://www.epa.gov/pfas/draft-interim-recommendations-addressing-groundwater-contaminated-pfoa-and-pfos

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Contact Information

Stephen M. Kline, P.E. Associate Principal GZA GeoEnvironmental of New York office: 212-594-8140 ext-8905 | cell: 347-242-7109 stephen.kline@gza.com | www.gza.com | LinkedIn

Thank you