Presentation_InfoItem_02L-PFAS_May2024_Shelton

15A NCAC 02L .0202 Groundwater Quality Standards PFAS Rulemaking
Bridget Shelton
Division of Water Resources
May 2024 GWWMC Informational Item
Types of North Carolina Water Quality Standards
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Groundwater Standards
(protect resource)Surface Water Standards
(protect resource)
Drinking Water Standards
(treatment)
Groundwater in NC
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•Groundwater is the water that fills cracks and other openings in beds of
rocks and sand and is stored in underground reservoirs known as aquifers
•Groundwater supports approximately 50% of drinking water use in the state
•Public Water Supply Sites
•80% of approximately 2300 Public Water Systems rely on groundwater
as drinking water source
•Private Drinking Water Wells
•25% of residents rely on groundwater sourced wells
•Water quality not regulated by state or federal agencies
National Ground Water Association:https://www.ngwa.org/what-is-groundwater/About-groundwater/groundwater-factsNC Environmental Education:https://www.eenorthcarolina.org/resources/your-ecological-address/groundwater
NC Groundwater Quality Standards
Federal Requirement No
North Carolina Rule 15A NCAC 02L .0202
Population Human Adults
Target use Ingestion
Household use
Standard endpoints
Noncancer
CancerAqueous taste and odor
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North Carolina Groundwater Quality Standards
•Maximum allowable concentrations which may be tolerated without creating a threat to human health or which would otherwise render the groundwater unsuitable for its intended best usage
•Best Usage: existing or potential source of drinking water supply for humans
•Protect groundwaters of the state as a resource for human consumption
•Implemented in various programs including site clean-ups, risk assessments, health evaluations, etc.
Groundwater Quality Standards Rule
Title 15A NCAC Subchapter 02L – Groundwater Classifications and Standards
Section .0100: General Considerations
Section .0200: Classifications and Groundwater Quality Standards
.0201 Groundwater Classifications
.0202 Groundwater Quality Standards
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•Substances which are not naturally occurring and for which no
standard is specified shall not be permitted in concentrations at or
above the practical quantitation limit (PQL).
•Where the standard for a substance is less than the PQL, the
detection of that substance at or above the PQL constitutes a
violation of the standard.
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Groundwater Quality Standards Rule Language
15A NCAC 02L .0202 (b) and (c)
Practical quantitation limit or "PQL" means the lowest concentration of a
given material that can be reliably achieved by analytical technique
during routine laboratory analysis.
Established as the least of the following:
1.Systemic/non-cancer threshold concentration
2.Concentration which corresponds to an incremental lifetime cancer
risk of 1x 10-6
3.Taste threshold limit value
4.Odor threshold limit value
5.Maximum contaminant level
6.National secondary drinking water standard
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Developing Groundwater Quality Standards
15A NCAC 02L .0202 (d)
Established as the least of the following:
1.Systemic/non-cancer threshold concentration
2.Concentration which corresponds to an incremental lifetime cancer
risk of 1x 10-6
3.Taste threshold limit value
4.Odor threshold limit value
5.Maximum contaminant level
6.National secondary drinking water standard
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Developing Groundwater Quality Standards
15A NCAC 02L .0202 (d)
Groundwater Standards Calculation
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1. Noncancer/systemic
𝐺𝐺𝐺𝐺𝐺𝐺𝐺𝐺=𝑅𝑅𝑅𝑅𝑅𝑅× 𝐵𝐵𝐺𝐺× 𝑅𝑅𝐺𝐺𝑅𝑅𝐺𝐺𝑅𝑅𝑅𝑅
2. Cancer 𝐺𝐺𝐺𝐺𝐺𝐺𝐺𝐺=𝑅𝑅𝑅𝑅× 𝐵𝐵𝐺𝐺𝑅𝑅𝐶𝐶𝐶𝐶× 𝐺𝐺𝑅𝑅𝑅𝑅
Toxicity benchmarks
RfD = Chronic Oral Reference Dose
CPF = Carcinogen Potency Factor
or Cancer Slope Factor (CSF)
Exposure estimates
RSC = Relative Source Contribution
(0.1 for inorganics; 0.2 for organics)
BW = Body Weight = 70 kg (adult)
WCR = Water Consumption Rate =
2 L/day (adults)
RL = Risk Level = 1x10-6
Groundwater Standards Calculation
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1. Noncancer/systemic
𝐺𝐺𝐺𝐺𝐺𝐺𝐺𝐺=𝑅𝑅𝑅𝑅𝑅𝑅× 𝐵𝐵𝐺𝐺× 𝑅𝑅𝐺𝐺𝑅𝑅𝐺𝐺𝑅𝑅𝑅𝑅
2. Cancer 𝐺𝐺𝐺𝐺𝐺𝐺𝐺𝐺=𝑅𝑅𝑅𝑅× 𝐵𝐵𝐺𝐺𝑅𝑅𝐶𝐶𝐶𝐶× 𝐺𝐺𝑅𝑅𝑅𝑅
Toxicity benchmarks
RfD = Chronic Oral Reference Dose
CPF = Carcinogen Potency Factor
or Cancer Slope Factor (CSF)
RL = Risk Level = 1x10-6
Definitions
RfD = an estimate of a daily exposure to
the human population that is likely to be
without an appreciable risk of deleterious
noncancer effects during a lifetime
CPF = an upper-bound estimate of the
increased human cancer risk from a
lifetime exposure to an agent
The following references are used, in order of preference:
1.EPA Integrated Risk Information System (IRIS)
2.EPA Drinking Water Health Advisories
3.Other EPA health risk assessment data
4.Other relevant, published health risk assessment data and
scientifically valid peer-reviewed published toxicological data
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15A NCAC 02L .0202 (e)
Developing Groundwater Quality Standards cont.
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Groundwater Standards Calculation Example
Calculation example from: 2022 Groundwater Triennial Review and Rulemaking, Supporting information (Aldrin) https://www.deq.nc.gov/about/divisions/water-resources/water-planning/classification-standards/groundwater-standards/groundwater-triennial-review-and-rulemaking
*Example of a calculation
sheet from a non-PFAS
chemical (Aldrin)
•Attachment A- Proposed Rule Text Amendment
•Attachment B-Calculation Sheets and Summary
Documents for Proposed PFAS Groundwater Standards
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Attachments
Per- and Polyfluorinated Substances (PFAS)
•Perfluorinated compounds are chemicals of specific concern
for North Carolina
•Evaluated the available scientific data to develop groundwater
standards for a subset of PFAS compounds
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American Water Works Associationhttps://www.awwa.org/Resources-Tools/Resource-Topics/PFAS
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Background – NPDWR for Drinking Water
•March 2023 – EPA announced the proposed National Primary Drinking Water
Regulation (NPDWR) for six PFAS:
•PFOA, PFOS, PFNA,HFPO-DA,PFHxS, and PFBS
•April 2024 – Finalized NPDWR, establishing legally enforceable levels for
drinking water, called Maximum Contaminant Levels (MCLs), for six PFAS:
https://www.epa.gov/sdwa/and-polyfluoroalkyl-substances-pfas
Background- Previous GWWMC and EMC Presentations
•November 2023 EMC Meeting
•Information Item- Proposed PFAS Toxicological Summaries
•January 2024 GWWMC Meeting
•Information Item- Affected Sources and Anticipated Implementation
Requirements; Cost and Benefits Analysis Approach
•March 2024 GWWMC Meeting
•Information Item- Plan Implementation Timeline; DWM Stakeholder
Meetings Overview and Feedback
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Proposed PFAS Compounds for Groundwater Standards Development
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PFAS Compound Acronym
1 Perfluorooctane sulfonic acid PFOS
2 Perfluorooctanoic acid PFOA
3 Hexafluoropropylene oxide dimer acid HFPO-DA (GenX)
4 Perfluorobutane sulfonic acid PFBS
5 Perfluorobutanoic acid PFBA
6 Perfluorohexanoic acid PFHxA
7 Perfluorononanoic acid PFNA
8 Perfluorohexane sulfonic acid PFHxS
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PFAS
Compound Reference Critical Health
Effects
Toxicity
Benchmarks and
Values Available
Proposed 02L
Standard (ng/L)
1 PFOS 2023 EPA Toxicity Assessment+Developmental and
Cardiovascular effects RfD, CSF, MCL 0.7
2 PFOA 2023 EPA Toxicity Assessment+Renal cell carcinomas RfD, CSF, MCL 0.001
3 HFPO-DA
(GenX)
2021 EPA Human Health Toxicity
Assessment+Liver effects RfD, MCL 10
4 PFBS 2021 EPA Human Health Toxicity
Assessment+Thyroid effects RfD 2,000
5 PFBA 2022 EPA IRIS Assessment Liver and Thyroid effects RfD 7,000
6 PFHxA 2023 EPA IRIS Assessment Developmental effects RfD 4,000
7 PFNA 2021 ATSDR* Minimal Risk Level+Developmental effects RfD, MCL 10
8 PFHxS 2021 ATSDR* Minimal Risk Level+Thyroid effects RfD, MCL 10
Proposed Groundwater Standards for PFAS Compounds
*ATSDR= Agency for Toxic Substances and Disease Registry
+Used as basis for EPA's PFAS National Primary Drinking Water Regulation​
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15A NCAC 02L .0202: Practical Quantitation Limit
15A NCAC 02L .0202 (b)(1):
Where the standard for a
substance is less than the
PQL, the detection of that
substance at or above the
PQL constitutes a violation
of the standard.
PFAS
Compound
Proposed 02L
.0202(h)
Standard (ng/L)
EPA PQL
(ng/L)*
Compliance
Level
1 PFOS 0.7 4.0 PQL
2 PFOA 0.001 4.0 PQL
3 HFPO-DA
(GenX)10 5.0 10
4 PFBS 2,000 3.0 2,000
5 PFBA 7,000 5.0 7,000
6 PFHxA 4,000 3.0 4,000
7 PFNA 10 4.0 10
8 PFHxS 10 3.0 10
*PQL reported by U.S. EPA as a Limit of Quantitation from national laboratory validation of the wastewater test
method (1633) (or for PFBA and PFHxA, set using the same methodology).
Stakeholder Meetings
January 2024
GWWMC/EMC
Info Items
November 2023, January 2024, March 2024, May 2024
GWWMC Action Item
July 2024
EMC
September 2024
Last day to file for
NC
Register
September 24, 2024
Notice of Text/
Public Comment
period begins
October 15, 2024
Public Hearing
October 30, 2024 (earliest)
End of Public Comment period
December 16, 2024
EMC
March 2025
Anticipated Timeline of Groundwater Standards PFAS Rulemaking
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Thank you
Bridget Shelton
Groundwater Quality Standards Coordinator
[e-mail]
(919)-707-9022
DWR, Classifications & Standards Branch:
https://deq.nc.gov/about/divisions/water-resources/planning/classification-standards