Washtenaw County, Salem Township, Arbor Hills Landfill, Inc.

Arbor Hills Landfill Inc PFOA + PFOS Sampling MapLast Updated: January 11, 2021

Background

Arbor Hills Landfill (Arbor Hills) is an active landfill located at the corner of Napier Road and Six Mile Road owned and operated by Advanced Disposal Services.  Samples were collected from this site in response to a letter from the Michigan Department of Environment, Great Lakes, and Energy (EGLE), requesting PFAS sampling of groundwater at a subset of site monitoring wells, as well as a representative leachate sampling.  The purpose of the PFAS sampling was to provide information on the composition of groundwater and leachate at the site.

Groundwater flows south-southeast; nearby surface water flows to the east.  Surface water from the site drains to Johnson Creek southeast of the site and into the middle branch of the Rouge River.

Recent Accomplishments

  • In March 2020, Arbor Hills Landfill was added to the MPART sites list and MPART recorded a webinar discussing PFAS around Arbor Hills. 
  • In April 2020, additional groundwater, sediment, and surface water samples were collected, to further define and characterize PFAS.  Covid-19 restrictions extended the scheduled timeline for reporting to EGLE.
  • On October 20, 2020, EGLE received a report from Arbor Hills Landfill documenting the April 2020 activities, results, and recommendations for additional PFAS characterization.  There groundwater samples were collected from on-site monitoring wells.  One monitoring well had a detection over criteria of 49 ppt PFOS and 26 ppt PFOA.  Based on the initial investigation and lack of conclusive findings, Arbor Hills submitted a workplan proposing additional sampling activities to help determine the source of PFAS.

Next Steps

  • EGLE will continue to review the Arbor Hills PFAS investigation activities to define the potential source and extent of the PFAS, both vertically and horizontally; to identify and evaluate potential receptors; and subsequent actions, if necessary. 
  • Arbor Hills is planning to conduct the additional recommended activities identified in the October 2020 PFAS report in the winter of 2021.

Residential Well Testing/Alternate Water Information

  • Municipal water is available in much of the area surrounding the landfill. However, several private wells are located to the west and south of the landfill.
  • Private wells were identified for sampling, and sampled, due to their proximity to Arbor Hills and well characteristics (e.g., within ½ mile, shallow screen, and/or unknown geology).  This includes a Type II well serving the landfill, and seven private residential wells.
  • PFAS results for the seven residential wells and one Type II well were below the Part 201 criteria for drinking water. 

Upcoming Community Engagement

  • None scheduled at this time.
Sampling Results Summary

This chart reflects data received after August 3, 2020.  Data prior to August 3, 2020 is reflected in the timeline below. 
This table was updated to include all seven PFAS criteria effective December 21, 2020.

Type of Sample

Date Sampled (or range)

Number of Sample Results Received

Number of Samples above Criteria*

Groundwater Monitoring Wells April 2, 2020 3 1
Surface Water April 2, 2020
 
2 2
Cumulative April 2, 2020 5 3

*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).
*Surface water samples are compared to Rule 57 non-drinking water values of 12 ppt for PFOS and 12,000 ppt for PFOA. 

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.
  • PFOS+PFOA result of 1,160 ppt was found in the leachate sample collected on June 11, 2019. There are no federal or state standards for these analytes in leachate. 
  • One residential well drinking water sample had 4 ppt PFHxA, this is significantly below the draft MCLs of 400,000 ppt for PFHxA.

Historical Timeline

  • In April 2019, EGLE requested that Arbor Hills collect PFAS water samples based on MPART initiatives.
  • On June 11, 2019, Arbor Hills collected five groundwater samples from on-site monitoring wells and one leachate sample from the primary leachate collection system.  The highest groundwater PFOS+PFOA result was 102 ppt from monitoring well, MPB-393.  No other monitoring wells results exceeded the EGLE Part 201 drinking water criteria for PFOS+PFOA (70 ppt).
  • On August 6, 2019, Arbor Hills collected a confirmation groundwater sample from monitoring well MPB-393.  The result was 124 ppt PFOS+PFOA.  In September 2019, EGLE received a summary of the PFAS sampling results from Arbor Hills.
  • In October 2019, EGLE reviewed the report prepared by Arbor Hills showing the PFAS data, and determined the next steps, including recommendations that Arbor Hills prepare a work plan to collect additional information related to PFAS.
  • On January 23, 2020, EGLE staff, Michigan Department of Health and Human Services (DHHS) and local health departments discussed the Arbor Hill’s PFAS results and potential residential well sampling, as well as the preparation of a public heath action plan to address potential issues and concerns, and proposed a Town Hall meeting to discuss PFAS around Arbor Hills.  Another planning call was completed on February 6, 2020 to finalize the residential sampling plan and discuss next steps.
  • On February 21, 2020, Arbor Hills provided EGLE the initial PFAS investigative work plan for review.  EGLE agreed with the activities and requested additional activities on February 24, 2020.
  • On February 26, 2020, seven residential water samples and one Type II water supply sample were collected for PFAS.  The results showed that none of the water tested were above the Part 201 for drinking water criteria or currently proposed MCL criteria.  
  • Historical Sampling Table: data is reflective of criteria prior to 8/3/2020:
    PFOS + PFOA Only
    This table reflects data received prior to 8/3/2020.

    Type of Sample

    Date Sampled

    Number of Samples

    Number of Results Received

    Number of Non-detects

    Number of Detections Below Standard*

    Number of Detections Greater Than Standard*

    Drinking Water (Residential Wells and Type II Wells) Feb 2020 8 8 8 0 0
    Groundwater June - Aug 2019 6 6 1 3 2
    Cumulative
     
    14 14 9 3 2

    *Groundwater results are compared to EGLE Part 201 Criteria of 70 ppt PFOS+PFOA.
    *Residential well results are compared to the USEPA Lifetime Health Advisory Level of 70 ppt PFOS+PFOA.