Wastewater Sludge/Biosolids PFAS Treatment Study

Background

Per- and polyfluoroalkyl substances (PFAS) are widely used chemical compounds that persist in the environment and are associated with various health issues. Several types of PFAS compounds are commonly detected in wastewater that enters treatment facilities through the sewer collection system.

The City has tracked, sampled and responded to PFAS regulation since these compounds were first discovered in the Pease drinking water sources in May 2014. (Go to a 10-Year History Timeline on Portsmouth's PFAS Treatment Efforts, 2014-2024)t

The City of Portsmouth maintains a multi-prong approach. Actions include:

• Sampling all Portsmouth drinking water sources quarterly for PFAS compounds to assess the 12-month rolling averages for the four New Hampshire regulated compounds. Working with regulators and other waterworks professionals to track and respond to the evolving water quality information, regulations and treatment technologies related to PFAS compounds.
• Evaluating the need for and piloting effective treatments that may be necessary at any other drinking water sources of supply serving the City’s drinking water system.
• Maintaining a dual resin and granular activated carbon treatment system for the Pease water system wells that removes the PFAS compounds. We have also been working with the Air Force monitoring and responding to PFAS compounds in the water sources in the Pease southern wellfield aquifer.
• Budgeting $7 million to design and install treatment on the Greenland Well, which is currently just over the 4 parts per trillion level of PFOA. An engineer is currently engaged in this design work, with bidding and construction anticipated in 2026.
• Undergoing preliminary design of treatment for the Portsmouth and Collins wells.

The City continues to comply with all standards regulating levels of PFAS in both the Portsmouth Regional and Pease International Tradeport Drinking Water Systems. Until the new 2025 Environmental Protection Agency (EPA) rule is finalized and its requirements go into effect, Portsmouth, along with all community water suppliers in New Hampshire, must continue to comply with the maximum contaminant levels (MCLs) for four PFAS compounds established by the NH Department of Environmental Services in 2019.

PFAS Treatment Strategies Study

Now the City is taking the lead on a study to assess sludge/biosolids management strategies. Since wastewater treatment processes do not destroy or remove PFAS compounds, facilities receiving wastewater containing these chemicals produce sludge/biosolids with measurable concentrations of PFAS. The presence of PFAS compounds in wastewater sludge/biosolids has increased disposal costs due to restrictions on land application, limited landfill capacity, and decreased beneficial reuse pathways. 

In recognition of the changing regulatory environment and potential impact of PFAS contamination of future disposal of wastewater sludge/biosolids, the City of Portsmouth was awarded funding from the New Hampshire Department of Environmental Services (NHDES) to conduct a study in partnership with AECOM (Chelmsford, MA) and Underwood Engineers (Portsmouth, NH) to assess costs and operational impacts of alternate sludge/biosolids management strategies, processing technologies, and disposal options. The goal of this study is to identify sludge/biosolids treatment and disposal pathways that help the City of Portsmouth and surrounding communities meet regulatory requirements in a sustainable and affordable manner.  

Project Description

The study consists of the following key elements:

1. Distribute an online survey to regional stakeholders to assess how PFAS contamination has impacted sludge / biosolids management and disposal.

2. Estimate current and projected sludge / biosolid production quantities regionally and within the City of Portsmouth.

3. Evaluate the technical and economic feasibility of implementing promising technologies that reduce sludge / biosolids volume or have the potential to destroy PFAS compounds in wastewater sludge / biosolids generated by the Pease and Peirce Island Wastewater Treatment Facilities. 

4. Analyze the data to determine if these technologies become more economically viable with increasing scale to assess whether a regional wastewater sludge / biosolids processing facility is a more feasible option.

5. Estimate the life-cycle cost and space requirements needed to implement promising treatment technologies at the Pease and Piece Island Wastewater Treatment Facilities. Other locations will be identified if a regional facility that serves multiple communities is the most viable option.