LD 1911 Wastewater Effluent Monitoring for Perfluoroalkyl and Polyfluoroalkyl Substances (PFAS) 2022-2023

The wastewater and groundwater data from this investigation was obtained as part of an ongoing Departmental study, pursuant to PL 2021, ch. 641, Act to Prevent the Further Contamination of the Soils and Waters of the State with so-called Forever Chemicals and is intended to reveal the qualitative and quantitative PFAS signatures of certain public and private (industrial and commercial) wastewater discharges throughout Maine.

Wastewater Effluent PFAS Monitoring Project

In September 2022, the Department initiated a wastewater effluent monitoring project(1) to require sampling for PFAS compounds in wastewater effluent from certain licensed discharges(2). Sampling commenced at 105 publicly owned treatment works (POTWs) and 19 private facilities (select businesses and industries) as follows:

  1. POTWs with surface water discharges subject to the Department’s toxics monitoring program.
  2. POTWs with biological treatment lagoons followed by spray irrigation to dedicated spray sites. These results include sampling data for both lagoon effluent and spray site groundwater monitoring wells.
  3. Private facilities with surface water discharges.
  4. Private facilities with biological treatment lagoons followed by spray irrigation to dedicated spray sites or subsurface discharge. Results include sampling data for both lagoon effluent and spray site groundwater monitoring wells.

The majority of facilities collected effluent data monthly for ten months. Groundwater data was collected at select facilities quarterly. All samples collected for this study were analyzed for 28 PFAS compounds by EPA method 537M(3). Results were entered into the Department’s Environmental and Geographic Analysis (EGAD)(4) database. Data reported in the facility reports was extracted from EGAD on November 15, 2023 and represents the results of all data analyzed at the study’s conclusion. All PFAS results are reported in the units ng/L (parts per trillion-ppt).

Results include 28 PFAS compounds and the Maine “Sum of 6”, which includes the following PFAS species that are used to derive the current state interim drinking water standard of 20 parts per trillion (ppt): perfluorooctanoic acid, perfluorooctane sulfonic acid, perfluorohexane sulfonic acid, perfluorononanoic acid, perfluoroheptanoic acid and perfluorodecanoic acid (abbreviated as PFOA, PFOS, PFHxS, PFNA, PFHpA, and PFDA). A final PFAS Sum of 6 for PL 2023, ch 641 project data was prepared in November 2023 and can be found at this link(5).

Questions regarding this project or data reported on this website should be directed to David Madore, Deputy Commissioner and Communication Director, 207-287-5842, David.Madore@maine.gov

PLEASE READ THE FOLLOWING EXPLANATION OF THE EFFLUENT MONITORING DATA REPORTED ON THE MAINE DEP PFAS INVESTIGATION INTERACTIVE MAP.

Explanation of the Wastewater Effluent Monitoring Project Data

The information listed on the Maine DEP PFAS Investigation Map represents the completed data set for the approximately 10-month study. Click on the geographic location of the sampling points (yellow pin icon) to see facility information and download the results in Excel.

For surface water dischargers, the yellow pin/blue circle icon represents the approximate location of the final effluent discharge point where the samples were collected. For lagoon effluent and monitoring well samples, the yellow pin/blue circle icon represents the approximate location where the sample was collected (lagoon effluent before spray or groundwater monitoring well).

All downloaded Excel Spreadsheets contain sample results with the facility name, MEPDES permit number, and effluent discharge location at the top of the table. The table lists the date, location, and results in ng/L (parts per trillion-ppt) for each sampling event that is recorded in the EGAD database.

The tables include the Maine PFAS Sum of 6 and the 28 PFAS species included in EPA 537M method of analysis. All results are reported in ng/L and include laboratory validation qualifiers where applicable. Laboratory validation codes used in these reports include the following:

ND = Non-detected   RL = Reporting Limit   MDL = Method Detection Limit
U = One or more of the PFAS six compounds was not detected at a level greater than the laboratory method detection limit (MDL).
J = One or more of the PFAS six compounds was detected at a level greater than the laboratory MDL and less than the reporting limit. J qualifiers indicate an unknown bias to the sample results.
B = Results has contamination in associated method blank, filed blank, equipment blank or instrument blank – results may be biased high

Note: An empty cell in the report means the data for that compound did not meet Department Quality Assurance/ Quality Control (QA/QC) criteria and was rejected. The “_A” listed next to the parameter name indicates that the compound was reported in the acid form.

Abbreviations used in these reports include:

MEPDES = Maine Pollutant Discharge Elimination System
WW = Wastewater   GW = Groundwater   TF = Treatment Facility   TP = Treatment Plant
WCPF = Water Pollution Control Facility
MW = Groundwater Monitoring Well

References and Links

  1. Information on PFAS and wastewater treatment facilities can be found at this link: Summary of Wastewater Effluent Monitoring Data - DEP 2022

  2. A table of facilities participating in the study and their MEPDES permit numbers can be found at this link: Facility List

  3. A table of the 28 PFAS compounds analyzed in EPA Method 537M and their abbreviations can be found at this link: PFAS Compound List

  4. See EGAD disclaimer at this link: EGAD Data Disclaimer

  5. A summary report of PFAS Sum of 6 for PL 2021, ch. 641 Wastewater Effluent Monitoring of participating facilities entered into EGAD as of November 15, 2023 can be found at this link: Project Summary Report