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Shiawassee Sanitary Landfill (Owosso Township, Shiawassee County)

EGLE Site Lead: Eric Van Riper, VanRiperE@Michigan.gov or 517-420-6785. Webpage last updated July 21, 2021.

Background

The former Shiawassee Sanitary Landfill was a gravel pit that became a licensed solid waste landfill that operated from 1967 to 1973. The former landfill encompasses approximately 11 acres in Owosso Township at the western edge of the City of Owosso. The site is bordered by residential development to the north and east, undeveloped land to the south, and the Owosso Township industrial park to the west.  A public water system services the area, however, individual water wells are still present in the area.  The Shiawassee River is located approximately 1.5 miles northeast of the site.

Groundwater contamination of volatile organic compounds (VOC's) has been documented leaving the landfill property, moving in a northeast direction, contaminating residential wells in the area.  A responsible party group (Group) for the landfill extended municipal water to the homes in the area as part of a settlement with EGLE.  Most of the homes have connected to municipal water, however, there are still 15 residential wells in the area where the owners have opted to remain on their residential well water.

The Shiawassee County Health Department requested an investigation into possible PFAS contamination at the site and the potential impacts on the remaining 15 residential wells.  On April 12-14, 2021, EGLE sampled 30 monitoring wells in and around the landfill to determine the presence of PFAS compounds at the former landfill.  The results showed PFAS compounds in 14 of the 30 monitoring wells exceeded the cleanup criteria.  The maximum concentration detected for PFOS was 110 parts per trillion (ppt) and the maximum concentration detected for PFOA was 88 ppt. 

As the result of PFAS compounds detected at the landfill, 12 of the 15 homes with private water wells were sampled for PFAS compounds on June 16, 2021.  The results of that sampling showed one residential well with PFOA contamination at 10 ppt.  No other residential wells had any PFAS compounds detections.  Arrangements are currently being made to provide a point-of-use filter(s) to the homeowner until that property is connected to municipal water.   

Shiawassee Sanitary Landfill Map

Recent Accomplishments

  • On June 16, 2021, EGLE sampled 12 of the 15 remaining residential wells in the area for PFAS compounds. 
  • On June 28, 2021, EGLE received the PFAS results from the June 16th residential well sampling.  The results showed one residential well with PFOA detected above the cleanup criteria at 10 ppt.  No other residential wells had PFAS compounds detected. 

Next Steps

  • The Shiawassee County Health Department will be providing point-of-use filters to the residential property where PFOA was detected above the cleanup criteria.  The health department will also be sending the homeowners PFAS results from the June 16th sampling event.   

Residential Well Testing/Alternate Water Information

  • A responsible party group for the landfill extended municipal water to the homes in the area as part of a settlement with EGLE, however, 15 residential wells remain where the owners opted to continue to use well water.  Funding is available through the responsible party group to connect the contaminated residential well to the available municipal water system. 

Upcoming Community Engagement

  • The Shiawassee County Health Department will be sending the PFAS sample results to the homeowners of the residential well sampling that was conducted on June 16, 2021.

Sampling Results Summary

Type of Sample

Date Sampled (or Range)

Number of Sample Results Received

Number of Samples above Criteria*

Groundwater Monitoring Wells

April 12 - 14, 2021 30 14
Residential Wells June 2021 - August 2021 17 1
*Residential well and groundwater monitoring well results are compared to EGLE Part 201 criteria for 7 PFAS compounds effective 12/21/2020:  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

  • None at this time.

Historical Timeline

    • On April 12-14, 2021, EGLE sampled 30 existing monitoring wells that were installed on or around the landfill property for PFAS and volatile organic carbon (VOC) analysis.
    • On May 11, 2021, EGLE received the PFAS results from the April 2021 sampling event.  The highest concentration of PFAS was 110 ppt for PFOS and 88 ppt for PFOA.
    • On June 16, 2021, EGLE sampled 12 of the 15 remaining residential wells in the area for PFAS compounds.
    • On June 28, 2021, EGLE received the PFAS results from the June 16th residential well sampling.  The results showed one residential well with PFOA detected above the cleanup criteria at 10 ppt.  No other residential wells had PFAS compounds detected.