In March 2022, an Aquatalk blog post discussed initial steps that EPA will likely be considering as it moves forward in developing a rule to address per- and polyfluoroalkyl substances (PFAS) that may include MCLs. As we discussed, there are many variables to consider and decisions to make. But at the beginning of the process we start with health considerations, and how to best address these with the rule. Acute and chronic health risks are considered along with vulnerable populations. This determination is yet to be made for PFAS, but it could have a profound influence on the structure and requirements of a federal PFAS rule. This second of three articles will examine the factors and variables that may go into establishing a PFAS rule with MCLs. Hopefully, this will help best prepare all of us to review EPA’s draft PFAS rule when it is published and provide constructive input to them during the comment period.
A monumental decision to make in any PFAS rule will be which public water systems are subject to the rule. Most public water systems in Colorado are non-community systems, and the majority of those service transient populations. Typically, rules for chronic contaminants do not apply to transient non-community systems, but do apply to non-community systems that serve non-transient populations, like large workplaces. Transient non-community systems tend to struggle the most with compliance, and considering the cost of PFAS monitoring and treatment, complying with a PFAS rule would be an enormous challenge for these systems. Implementing the rule for these systems would also be very challenging for states. Some states have applied or at least partially applied their PFAS rules to transient non-community systems, in some cases this is based on vulnerability to PFAS contamination.
Once it is determined which systems the PFAS rule will apply to, next the monitoring framework, analytical methods, and laboratory certification requirements need to be established. States will need to establish certification programs, minimum reporting levels, and quality assurance/quality control reviews for labs conducting PFAS analysis. Monitoring for chemical contamination typically takes place at all system entry points, and sometimes compositing samples can be done. Typically, initial monitoring would take place with four quarterly samples, although some states also required confirmation testing if PFAS values above certain thresholds were found. Counting previously collected data for initial monitoring and reduced monitoring is also likely to be considered by EPA. For example, will samples collected under the Unregulated Contaminant Monitoring Rule (UCMR) that is done from 2023 to 2025 be allowed to count for initial monitoring? If PFAS are not detected during initial monitoring or only found at very low levels, will reduced monitoring be allowed after that?
EPA will also need to decide how compliance will be determined. For chronic health risk contaminants this is typically done using a running annual average, but for acute risk contaminants this is often done as the average of one result with a confirmation sample. What are the immediate next steps if the MCLs are exceeded? For chronic constituents, Tier 2 public notice needs to be provided no later than 30 days after the exceedance, and water systems must take steps to come into compliance. If this involves installing treatment, projects of this nature can take multiple years to implement. For acute contaminants, Tier 1 public notice is required within 24 hours, and usually comes with advice to consume an alternate source of water. This situation is quite disruptive to schools, restaurants and businesses, and the entire community, particularly for individuals that need to rely on others for water delivery.
If a public water system cannot regain compliance with the PFAS MCLs by shutting off wells or blending with other sources, then they would likely need to install treatment. At present, the most likely treatment technologies to be deployed in Colorado would be granular activated carbon or ion exchange resins. There are advantages and disadvantages to each technology, but they involve added costs, likely changes to operator certification requirements and treatment residual handling and disposal concerns and costs. These must all be taken into consideration as EPA considers what Best Available Technologies (BAT) are for PFAS. EPA will also need to examine health benefits and overall costs in their draft PFAS rule.
In our next blog, we will discuss additional considerations involved with regulating PFAS and the possibility that EPA will regulate PFAS as a group, similar to how disinfection by-products are regulated, and require treatment techniques to remove PFAS, similar to the approach for cryptosporidium.
Thank you for being dedicated to providing safe drinking water for all!
➽ Ron Falco, P.E. Safe Drinking Water Program Manager
