The debate regarding the most appropriate method to collect non-potable liquids—specifically POTW influents and effluents—continues. Last month California State Water Quality Control Board (SWQCB) staff appeared to walk back parts of the original Phase III PFAS monitoring orders, directing the responsibility for making decisions regarding sampling techniques back to the agency and their laboratory. October is upon us and water treatment professionals are wondering which way to go. Here are a few facts and practical consideration to ponder as QAPPs and SLAPs are prepared.
-Requires 24 hour composite sampling of influents, effluents, and RO concentrates.
-Requires the collection of equipment blanks should any autosampler parts contain fluoropolymers.
-Order states that samples must be representative of wastes and discharges.
-Requires POTW’s with existing monitoring wells to submit a monitoring plan for RWQCB approval.
-Requires monitoring wells to be sampled according to existing QAPP collection protocols, ie. grabs.
-Recommends the creation of a Quality Assurance Project Plan (QAPP).
-Directs the POTW to “…consult with the laboratory performing the analysis” regarding sample collection, i.e. grab or composite.
PFAS by SPE and LCMSMS in accordance with DoD QSM Table B-15 of QSM
-Sub-sampling from the original collection vessel is not permitted.
-Requires the complete liquid sample extraction and rinsing of collection vessel onto the solid phase extraction media.
-Dilution is possible only via collection of separate containers containing smaller volumes.
Take Aways
In most situations, Babcock Labs recommends that samples for PFAS analysis be collected via grab sampling technique. As with other potential contaminants such as oil and grease or other semi-volatile constituents, the method of extraction makes composite sampling impractical and increases the potential for bias because target analytes can be lost on every container or device used during collection. In the case of PFAS, grab sampling reduces the risk of accidental contamination from devices and surfaces containing fluoropolymers. Grab sampling may also reduce or eliminate the need for additional equipment blanks.
Babcock field and lab staff have extensive experience writing and implementing project plans. We routinely support large project QAPPs under the authority of the regional boards, the Department of Toxic Substances (DTSC), and the USEPA. Our field team also has collected PFAS samples for a variety of matrices including non-potable liquids. Please contact us for assistance with non-potable PFAS sampling for more information.