Developing a Permanent Post-Release PFAS Remediation Solution
In October 2016, buildings, tanks, infrastructure, and paved surfaces at a construction manufacturing facility in upstate New York became contaminated with per- and polyfluoroalkyl substances (PFAS) following the use of aqueous firefighting foam (AFFF). AFFF was used to extinguish a petroleum tank fire. Although PFAS-containing AFFF is no longer manufactured in the US, warehoused unlabeled AFFF-containing PFAS still exist.
The New York State Department of Environmental Conservation (NYSDEC) required the containment of AFFF rinse water and all subsequent stormwater to prevent offsite migration. The site stormwater drained to surface water used as a public water supply. NYSDEC would allow our client to resume discharge upon demonstrating PFAS concentrations remained below USEPA drinking water health advisory levels. Until then, facility operations were restricted.
To prevent further offsite migration, our client lost use of areas where stormwater accumulated. Antea Group was tasked with developing a permanent remedial solution for management of the PFAS release, such that the facility could resume full operations. Antea Group’s strategy involved a gap analysis, remedial alternatives assessment, PFAS extent assessment plan, and report for remedy selection and NYSDEC approval.
Antea Group was retained to act as the NYSDEC-qualified environmental professional. We assessed the source, nature, and extent using a PFAS-specific sampling method and evaluated potential migration pathways. We also assessed the extent of PFAS on infrastructure, pavement and soil, and located the source hot spots. Antea Group evaluated the effectiveness of cleaning and flushing with rain water, rate of degradation, and trend analysis. We developed a preliminary design and cost to install and operate a stormwater carbon treatment system and compared that to the cost risk benefit of ongoing containment and disposal versus the cost of a removal action.
Antea Group provided the client with a cost saving closure strategy that was approved by NYSDEC with a No Further Action within three months of implementing the remedy. Given the recalcitrant nature of perfluorooctane sulfonate (PFOS) – a constituent of AFFF – a removal remedy was most protective, fastest, and least costly. Of the compounds within the PFAS group, PFOS, was recalcitrant to natural attenuation and remained elevated in concentration several orders of magnitude above target levels with no decreasing trend. The other PFAS compounds had decreased significantly to below detection or advisory levels. Frequent cleanings (400,000 gallons of stormwater) were not reducing the PFOS concentrations. Therefore, we found that if either a carbon treatment or continued offsite disposal stormwater management remedies were selected and operated for five years, the cost would far exceed the cost of a removal action.
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