Isabella County Landfill (Mount Pleasant, Isabella County)

• On June 4, 2019, due to known groundwater contamination from contaminants other than PFAS, as well as proximity to private residential wells and the Chippewa River, Isabella County’s environmental contractor collected PFAS samples from 6 onsite monitoring wells.
• On July 9, 2019, EGLE received the results of the June 2019 groundwater sampling event from Isabella County. The highest results were 100 ppt PFOS+PFOA and 218 ppt Total Tested PFAS.
• On July 30, 2019, the final investigation report was shared with EGLE.
• During the week of September 16, 2019, Isabella County collected samples in 13 additional onsite groundwater monitoring wells as well as sediment from a former discharge channel to determine the extent of PFAS contamination.
• On November 5, 2019, EGLE received the results from the groundwater sampling conducted in September 2019.  The results are reflected on the sampling table.
• On December 10, 2019, EGLE received PFAS testing results from the sediment in the site’s former discharge channel at the northeast area of the site. PFAS constituents were not detected in the sediment samples.

• On February 18, 2020, EGLE approved Isabella County’s surface water sampling work plan for the quarry lake located immediately to the east of the landfill. 
• On May 1, 2020, Isabella County sampled the quarry lake immediately to the east of the site for PFAS analysis.
• On June 23, 2020, EGLE received PFAS results from the May 1, 2020 sampling event.  PFAS were non-detect in the sample.
• On August 18, 2020, EGLE requested that Isabella County continue PFAS monitoring onsite.
• In December 2020, Isabella County sampled eight monitoring wells onsite for PFAS. 

*Groundwater results are compared to EGLE Part 201 Criteria of 70 ppt PFOS+PFOA.

• On January 29, 2021, EGLE received PFAS results from a December 2020 groundwater monitoring well sampling event.  Eight onsite monitoring wells were sampled, three of them had PFOA over criteria. Monitoring wells sampled along the property boundary did not contain PFOA or other PFAS constituents above criteria. 
• On June 18, 2021, EGLE received PFAS results from a March 2021 groundwater monitoring well sampling event. Nine monitoring wells were sampled for PFAS. Three of the eight wells sampled had PFOA over criteria.

• On February 10, 2022, EGLE received PFAS results from a December 2021 groundwater monitoring well sampling event. Nine monitoring wells were sampled for PFAS. Two of the nine wells sampled had PFAS over criteria.

Sampling Results Summary

* 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).

Sampling Notes

• On August 3, 2020, new Part 201 Criteria went into effect.  Historical sampling data compared to Part 201 Criteria >70 is captured in the historical timeline below.
• Other PFAS analytes were detected in samples. There are no federal or state standards for these analytes.
• A quarry lake is located on the property immediately downgradient of the landfill, and further downgradient is the Chippewa River and the Hubscher Pit, a quarry lake connected to the Chippewa River.