Background

Town of Nantucket’s vendor Waste Options Nantucket (WON) under a co-permit with Town performed sampling and testing of Nantucket Natural Compost (co-compost) product for PFAS compounds in compliance with the Approval of Suitability (AOS) permit. The Town has also contracted with CDM Smith to perform groundwater and surface water sampling for PFAS. All testing is performed using appropriate protocol and a laboratory approved by Massachusetts Department of Environmental Protection (Mass DEP).

Waste Options Nantucket (WON) Activities

General Information
Nantucket Natural Compost (co-compost) comes from organic Municipal Solid Waste (compostable waste) from the residents and businesses of Nantucket. The co-compost also includes dewatered sludge, which is an output from the Waste Water Treatment Facilities (WWTFs) that serve Nantucket. The Municipal Solid Waste combined with dewatered sludge is processed through our large industrial drum and then screened and further processed through the compost facility. The product is then mixed with leaf/yard waste and windrowed outside for six months to finish. WON is sampling the Nantucket Natural Compost (co-compost) as required by the AOS permit. PFAS sampling every three months was recently added to the AOS permit requirements. Sample collection and laboratory analysis is performed to meet MassDEP general PFAS sampling and laboratory guidelines. MassDEP and U.S. Environmental Protection Agency do not currently have PFAS standards for dewatered sludge, biosolids (treated sludge) or co-compost.

Environmental Sampling

Beginning in 1997, CDM Smith has been conducting environmental sampling at the Nantucket Landfill site on Madaket Road for groundwater, surface water, and landfill gas. The monitoring and reporting activities are regulated under the MassDEP Solid Waste Management Regulations (310 CMR 19.132) and the approved Environmental Monitoring Plan (EMP) (SECOR, 1999), which includes semi-annual groundwater and surface water monitoring and quarterly landfill gas monitoring.  

CDM Smith has performed four rounds of PFAS sampling (October 2023, April 2024, October 2024, April 2025) of groundwater and surface water from existing environmental monitoring stations at the landfill site. This work was conducted in accordance with the Massachusetts Department of Environmental Protection (MassDEP) Solid Waste Division permit approval letter dated September 1, 2023. The basis of this approval was the Nantucket Landfill, Nantucket, Massachusetts Application for a Minor Modification BWP SW-22: Landfills – Minor Modification - PFAS Groundwater and Surface Water Sampling Work Plan and Quality Assurance Project Plan (QAPP) submitted by CDM Smith on December 3, 2021, which can be accessed here.

PFAS data collected has since been summarized and presented in the following reports to the Town of Nantucket and MassDEP:

• PFAS Groundwater and Surface Water Sampling Report – October 2023, Nantucket Landfill (CDM Smith, January 24, 2024), here
• PFAS Groundwater and Surface Water Sampling Report – April 2024, Nantucket Landfill (CDM Smith, August 30, 2024), here
• Semi-Annual Groundwater Surface Water and Landfill Gas Monitoring – October 2024, Nantucket Landfill (CDM Smith, December 6, 2024):
  • Nantucket LF - October 2024 Semi-Annual PFAS Water Quality Results
  • Nantucket LF - October 2024 Semi-Annual Solid Waste Water Quality Results
• Semi-Annual Groundwater Surface Water and Landfill Gas Monitoring – April 2025, Nantucket Landfill: PFAS data were collected in April 2025, and a nature and extent evaluation based on the latest data is in preparation. However, the raw data are included in the April 2025 Semi-Annual Groundwater and Surface Water Monitoring Report here.

Each sampling report includes the September 1, 2023 permit approval letter as Appendix A.

At the request of MassDEP, a Statement of Work and a SW-22 Minor Modification Permit is being prepared for a PFAS nature and extent investigation, including one additional round of PFAS sampling of groundwater and surface water at the Nantucket Landfill, to be performed in April 2025. The contract for that work is available here.

The Town of Nantucket has also hired Sanborn Head Associates to conduct an initial PFAS characterization of soils within the landfill boundary. The contract for that work is available here. On March 28, 2025, Sanborn Head, on behalf of the Town, submitted an SW45 application for a proposed PFAS characterization and assessment of reclaimed soils to determine whether these soils may be contributing to PFAS concentrations previously detected in groundwater and surface water on and near the landfill. This proposed soil sampling program is aimed at aiding the PFAS groundwater and surface water nature and extent evaluation that CDM Smith is performing on behalf of the Town.