North Post of Camp Grayling Area of Interest (Waters, Otsego & Crawford Counties)

Lisa Kruse, KruseL@Michigan.gov or 989-370-1424.

The Army National Guard (ARNG) sampled for PFAS at the North Post of Camp Grayling, including Range 40. This investigation followed the Comprehensive Environmental Response, Compensation, and Liability Act (CERCLA) process due to information indicating the possibility of release of PFAS through use of firefighting foams and wetting agents.

In 2021, one round of PFAS groundwater samples was collected by ARNG from a limited number of existing Range 40 monitoring wells during the Site Inspection (SI) stage of CERCLA. Although PFAS compounds had not been detected on site exceeding groundwater clean-up criteria or in lakes and streams exceeding Water Quality Values, additional characterization was necessary by ARNG to complete the SI absence or presence investigation. Due to data gaps in the initial SI, the ARNG conducted a Supplemental SI investigation in October 2023.

Because the absence or presence of groundwater contamination at Range 40 was not fully investigated in 2023, MPART conducted precautionary drinking water well sampling on the east side of Guthrie and Section One Lakes as well as between Jones Lake and southern Range 40.

Historically, Range 40 groundwater was monitored for metals and explosives associated with the active air-to-ground range. Based on sampling at Range 40, groundwater flows to the southeast. Previous studies indicate a connection between groundwater and groundwater-fed lakes and rivers surrounding Range 40.

Range 40 lies within four watersheds: Chub Creek (northwestern range); Crapo Creek North Branch Au Sable River (northeastern range); Kyle Lake (southeastern range); and East Branch Au Sable River (central and southwestern range).

The groundwater-fed East Branch of the Au Sable River runs through the western side of Range 40 and connects groundwater-fed Barnes, River, and Jones Lakes. Shallow groundwater flow direction likely follows a southwesterly direction in the area of the East Branch Au Sable.

The headwater lakes on the northwestern portion of Range 40 and just off-site to the northwest - Marsh, Section One, and Guthrie Lakes - are hydraulically connected. Shallow groundwater flow direction possibly follows a more northerly direction in the area of the headwater lakes connected by Chub Creek.

There are numerous other investigations in this area that have become MPART sites: Camp Grayling - Lake Margrethe; Camp Grayling - MATES at Range 30 Grayling Army Airfield; and Grayling Wastewater Treatment Facility Discharge Fields.

There is currently no municipal water available in the areas. Residents are on private drinking water wells.

EGLE conducted precautionary private drinking water well sampling on the east side of Guthrie and Section One Lakes, closest to Range 40, as well as between Jones Lake and southern Range 40. Of the 74 private drinking water wells canvassed near Range 40 in April 2023, 35 returned access agreements and were sampled. Of the sampled private drinking water wells, three wells had detections of PFAS below Michigan Drinking Water Criteria.

The two Jones Lake Campground wells were sampled in April 2023. One well was non-detect for PFAS. The other well had detections of PFOA below Michigan Drinking Water Criteria for two rounds of sampling and the well was taken offline by the DNR.

Based on the ARNG North Post SI and Supplemental SI results, a No Further Action under CERCLA is recommended at this time. Additionally, no further drinking water sampling is expected by EGLE due to the results of the 2023 precautionary private drinking water well sampling.