Grayling Wastewater Treatment Facility Discharge Fields (Grayling, Crawford County)
EGLE Site Lead: Sydney Ruhala, RuhalaS@Michigan.gov or 517-599-5356. Content last updated: August 4, 2022.
The city of Grayling operates the Grayling Wastewater Treatment Facility (WWTF), which is an approximately 35-acre wastewater treatment system that went into operation in 1990. The WWTF includes 5 wastewater lagoons that are lined with a PVC membrane and underlain by geosynthetic clay liner. The wastewater lagoons discharge to irrigation fields approximately 145 acres in area and three-quarters of a mile east of the WWTF at the south end of Industrial Street. The irrigation fields have monitoring wells that are sampled biannually in accordance with the groundwater discharge permit issued by EGLE’s Water Resources Division (WRD). The results of the analyses are submitted to WRD as required. Historically, analyses required by the groundwater discharge permit have not included PFAS.
On June 11, 2020, at the request of EGLE’s Remediation and Redevelopment Division (RRD), the city of Grayling allowed EGLE contractors to sample the groundwater using two of the WWTF’s monitoring wells at the northern end of the irrigation fields. RRD’s request was based upon recent reports of foam on Shellenbarger Lake and the possibility that Grayling Army Airfield (MPART site) contamination was making its way into the sanitary sewer system.
The sampling results identified PFOA, PFOS, and other PFAS compounds in the two groundwater monitoring wells. PFOA and PFOS were identified at concentrations exceeding Part 201 Drinking Water Cleanup Criteria for PFOA and PFOS at 8 ppt and 16 ppt, respectively.
Shallow groundwater flows to the north toward Shellenbarger Lake, while the deeper groundwater aquifer is estimated to flow in a more northeasterly direction. EGLE is working with the city of Grayling to identify potential sources in the sanitary sewer system and to identify receptors downgradient of the discharge fields.
- On May 5, 2022, the city of Grayling sampled the influent, effluent and one groundwater monitoring well at the WWTF. The City also resampled an additional two groundwater monitoring wells at the WWTF. PFOA, PFOS, PFHxS, and/or PFNA were detected in two of the monitoring wells above criteria. The highest results were 46.7 ppt PFOA, 58.6 ppt PFOS, 104.5 ppt PFHxS, and 13.15 ppt PFNA.
- EGLE will continue to work with the city of Grayling to identify and reduce sources of PFAS contamination to the WWTF.
Residential Well Testing/Alternate Water Information
- EGLE in coordination with the Michigan Department of Health and Human Services and the local health department will expand residential well sampling if determined to be necessary.
Upcoming Community Engagement
- None at this time.
Sampling Results Summary
Type of Sample
Number of Sample Results Received
Number of Samples Above Criteria
|Residential Wells||October 2020||15||0|
|Groundwater Monitoring Wells||June 2020 - May 2022||3||2|
* Residential well and groundwater monitoring well results are compared to EGLE Part 201 criteria for 7 PFAS compounds: PFOS (16 ppt), PFOA (8 ppt), PFNA (6 ppt), PFHxS (51 ppt), PFHxA (400,000 ppt), PFBS (420 ppt), and HFPO-DA (370 ppt).
- None at this time.
- On June 11, 2020, EGLE contractors collected groundwater samples from two monitoring wells located on the north side of the Grayling WWTF irrigation fields and submitted for PFAS analysis.
- On July 7, 2020, EGLE received the results from the June 2020 groundwater sampling event from the lab. Results indicated that PFAS compounds were detected in samples from the two groundwater monitoring wells. The highest PFOA detection at 48 ppt and the highest PFOS detection at 43 ppt.
- On July 21, 2020, EGLE hosted an online meeting with the city of Grayling, Department of Military and Veterans Affairs (DMVA), and National Guard Bureau (NGB) to discuss the June groundwater sampling PFAS results from the two wells at the north end of the discharge fields.
- On August 3, 2020, EGLE representatives toured the city of Grayling WWTF and sanitary sewer collection system to determine sampling points to identifying source(s) of PFAS contamination.
- On September 17, 2020, MPART hosted a PFAS Regional Information Webinar for the Northern Region where details of this site investigation were presented.
- On October 1, 2020, EGLE’s contractor completed sampling of private drinking water wells directly downgradient of the Grayling WWTF.
- On October 21, 2020, EGLE received the sampling results from the October 1, 2020, private drinking water wells directly downgradient of the Grayling WWTF. All results were below drinking water criteria.
- On April 26, 2021, EGLE, in coordination with the city of Grayling, conducted sanitary sewer sampling to identify sources of PFAS contamination to the WWTF.
- On May 20, 2021, EGLE received the results from the April 2021 sanitary sewer sampling. PFAS was detected in all 11 sampling locations.
- On August 25, 2021, EGLE issued a Compliance Communication to the city of Grayling requesting sampling of the influent, effluent and several groundwater monitoring wells to better understand PFAS at the WWTF.
- On March 12, 2022, the city of Grayling submitted the work plan requested in the August 25, 2021, Compliance Communication. The work plan was approved by EGLE on March 31, 2022.