MassDEP Proposes Stringent MCL and Finalizes Cleanup Standards for Six PFAS

On December 13, 2019, the Massachusetts Department of Environmental Protection (MassDEP) announced two significant actions addressing per- and polyfluoroalkyl substances (PFAS) in Massachusetts. First, MassDEP is proposing regulations that will set the maximum contaminant level (MCL) for drinking water at 20 parts per trillion (ppt) for six PFAS, combined. MassDEP’s proposed MCL is among the lowest proposed or adopted by any state. Second, MassDEP is promulgating final regulations that set the groundwater cleanup standard at the same level: 20 ppt for six PFAS, combined. This concentration is significantly lower than the federal health advisory level of 70 ppt for only two PFAS, combined. Both of these regulatory actions became available on MassDEP’s web site on December 13, 2019, and will be formally published in the Massachusetts Register on December 27, 2019. 

Massachusetts is regulating six PFAS, listed below.

  • Perfluorooctanesulfonic acid (PFOS)
  • Perfluorooctanoic acid (PFOA)
  • Perfluorodecanoic acid (PFDA)
  • Perfluoroheptanoic acid (PFHpA)
  • Perfluorohexane sulfonic acid (PFHxS)
  • Perfluorononanoic acid (PFNA)

These six compounds were selected by MassDEP’s Office of Research and Standards. A technical document supporting this selection is expected but has not yet been made available on MassDEP’s website.

The Proposed Drinking Water MCL

MassDEP’s proposed MCL of 20 ppt for the six PFAS (combined) identified above would apply to all Community Water Systems (e.g., cities and towns) and Non-Transient Non-Community Systems (e.g., schools and larger businesses). These systems would be required to conduct monitoring for PFAS on a quarterly basis for one year, followed by less frequent monitoring, if warranted. Other provisions include required actions when PFAS is detected, monitoring protocols, and language on PFAS health effects for Consumer Confidence Reports. 

Transient Non-Community systems would be required to take one sample and analyze it for PFAS. The results must be reported to MassDEP. 

Implementation of the rule will be staggered as follows:

System size or type Initiate monitoring by Impact
50,000 consumers
or more
April 1, 2020 20 systems serving
4.3 million people
More than
10,000 consumers
October 1, 2020 106 systems serving
2.6 million people
10,000 consumers
or less
October 1, 2021 569 systems serving
708,000 people
All transient
September 30, 2022 Not indicated

Final Changes to State Cleanup Regulations

Effective December 27, 2019, MassDEP is amending the state cleanup program, known as the Massachusetts Contingency Plan (MCP), to include final standards for six PFAS. MassDEP issued these regulatory changes after receiving 51 comments during the public comment period. The major change made in response to these comments was to increase (make less strict) the soil standards based on studies conducted in Vermont that suggest that background levels of PFAS are higher than MassDEP initially considered. A more detailed response-to-comments document is expected but has not yet been made available by MassDEP.

Reportable Quantities and Reportable Concentrations

The MCP revisions set reportable quantities and reportable concentrations for six PFAS for groundwater and soil, which trigger an obligation to report the release to the state. The standards are:

quantity (lb)
GW-1 (mg/L)
Potential drinking
water area
GW-2 (mg/L)
All other
S1 (mg/kg)
S2 (mg/kg)
Other soils
Combined total See individual
compounds below
0.00002 See individual
compounds below
See individual
compounds below
See individual
compounds below
PFOA 1 See above 40 0.00072 0.4
PFOS 1 See above 0.5 0.002 0.4
PFDA 1 See above 40 0.0003 0.4
PFHxS 1 See above 0.5 0.0003 0.4
PFNA 1 See above 40 0.00032 0.4
PFHpA 1 See above 40 0.0005 0.4

Groundwater Cleanup Standards

The MCP revisions set “Method 1” cleanup standards for the six PFAS for groundwater. Method 1 standards can be used at any site by comparing exposure point concentrations to the standard. The final rule sets the following standards:

GW-1 (ppb)
Applies to potential
drinking water areas
GW-2 (ppb)
Applies to areas
near structures

GW-3 (ppb)
Applies to all
groundwater in MA

Combined total 0.02

See individual
compounds below

See individual
compounds below
PFOA See above N/A 40,000
PFOS See above N/A 500
PFDA See above N/A 40,000
PFHxS See above N/A 500
PFNA See above N/A 40,000
PFHpA See above N/A 40,000

Soil Cleanup Standards

The MCP revisions also set Method 1 cleanup standards for the six PFAS for soil. The standards differentiate between soil that is more accessible to people (e.g., S-1) and soil that is less accessible (e.g., S-3), and take into account potential impacts to groundwater. The newly established standards for the most accessible soils, S-1 are:

S-1 Soil (ppm) in areas that are:
GW-1 GW-2 GW-3
PFOA 0.00072 0.3 0.3
PFOS 0.002 0.3 0.3
PFDA 0.0003 0.3 0.3
PFHxS 0.0003 0.3 0.3
PFNA 0.00032 0.3 0.3
PFHpA 0.0005 0.3 0.3

According to MassDEP, a technical support document for the final rule will be made available on or before December 27, 2019.

The Final Word

The drinking water MCL and the groundwater cleanup standard for groundwater that may be used as drinking water are necessarily linked. MassDEP has informally stated that it expects the MCL and the GW-1 cleanup standard to be the same. As a result, if the process of developing an MCL results in a different standard than the 20 ppt level that has been proposed, the cleanup standard will likely be reopened and changed to meet that new level.

The comment period for the drinking water MCL opens on December 27, 2019, and closes at 5:00 pm on Friday, February 28, 2020. MassDEP will be holding five public hearings at different locations across the state in January 2020 to seek additional comment.

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