PFAS inventory and source identification: Finding where PFA enters collection systems

KEY TAKEAWAYS:

• The PFAS inventory helps determine where PFAS might be entering the collection system and who might be contributing.
• Illinois NPDES permit special conditions generally require permittees to develop and submit a PFAS inventory within 12 months of the permit effective date.
• Common high-risk PFAS contributors include airports and firefighting facilities, landfills, industrial manufacturers and metal finishing and plating facilities.
• The PFAS inventory process usually includes industrial surveys, safety data sheet review and industrial activity evaluation.

When PFAS sampling results come back, many wastewater treatment plant (WWTP) managers have the same reaction.

That's because the numbers confirm what they already expect: PFAS are present.

Sampling is the first step in the new Illinois NPDES permit requirements, but it only answers one question: What is in the wastewater? It does not explain how those compounds got there or who might be contributing them to the collection system.

That is the purpose of the PFAS inventory required for the NPDES permit from the Illinois Environmental Protection Agency (EPA). Sampling tells you what is present. The inventory helps determine who might be contributing.

Under Illinois NPDES permit language, the Illinois EPA special condition requires facilities to complete a PFAS inventory within 12 months of the permit's effective date and update that PFAS inventory every year for the life of the NPDES permit.

For many facilities, this Illinois EPA special condition requirement will take more time and coordination than the initial monitoring phase. Yet, it's a crucial step in permit compliance.

Under the Illinois NPDES permit, WWTPs are rarely the original source of PFAS. Most compounds enter the system upstream through industrial users, commercial operations, landfills, airports or simply from everyday consumer products that wash down the drain.

Because conventional treatment processes are not designed to remove PFAS, these compounds often pass through the plant or become concentrated in biosolids. That makes source identification a priority so facilities can reduce PFAS loading before it reaches the treatment plant.

The PFAS inventory reflects that approach. Instead of relying on expensive treatment upgrades, the permit framework focuses on identifying contributors and reducing discharges at the source.

Within 12 months of the permit's effective date, the permittee must develop and submit a PFAS inventory identifying potential contributors within the collection system. This PFAS inventory usually includes industrial users, commercial facilities and other relevant contributors such as hauled waste sources and significant indirect dischargers that might be releasing to the sewer.

Facilities should maintain and update the inventory as new information becomes available, , documenting any changes in contributors, new industrial connections, updated survey information or additional sampling results.

These permit timelines are firm, which means most facilities must begin the PFAS inventory process well before the first Illinois EPA reporting deadline.

The PFAS inventory should cover all potential contributors. From there, the level of review can be prioritized based on risk and available information.

Common high-risk contributors identified during your inventory include:

• Airports and firefighting training facilities.
• Landfills and landfill leachate sources.
• Industrial manufacturers and processors.
• Facilities using PFAS-containing coatings, surfactants or foams.
• Metal finishing, plating, textile, chemical or plastics operations.
• Commercial laundries and vehicle washing facilities.

The PFAS inventory follows a similar workflow used for industrial pretreatment programs, but with additional focus on PFAS-containing products.

The inventory process usually includes industrial surveys, safety data sheet review and industrial activity evaluation.

PFAS inventory surveys ask facilities to describe operations, water use, waste disposal practices and chemical products. Safety data sheets are reviewed to identify fluorinated compounds, trade names associated with PFAS or CAS numbers linked to known PFAS substances.

One challenge is that PFAS are not always listed clearly in product documentation. Some compounds are present in small amounts or under proprietary names, which can make source identification time-consuming.

Facilities can also consider PFAS precursors and the potential for precursor transformation, depending on the level of evaluation, because these compounds might not appear in routine monitoring but can transform into regulated PFAS compounds over time.

Because of these factors, the inventory phase often requires more coordination with industrial users than utilities initially expect.

The PFAS inventory is not a standalone requirement. The PFAS inventory feeds directly into the next step of the NPDES process, which is the PFAS reduction initiative.

Although the PFAS inventory required by the state is not due until 12 months after the permit becomes effective, waiting too long can create unnecessary pressure. Surveys take time to distribute and collect. SDS reviews can involve hundreds of products. Follow-up sampling might require coordination with laboratories and industrial users.

Starting early helps facilities meet their permit deadlines without rushing the PFAS inventory process. With the right planning and our expert guidance, the PFAS inventory requirement can become a manageable part of permit compliance rather than a last-minute scramble.

This is the third blog post in a series about PFAS regulations and their impact on the design and operation of wastewater treatments plants. Read the most recent blog post in this series or read the first post to learn everything you need to know about PFAS regulations.