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, it still exists at warehouses in unlabeled containers.
The New York State Department of Environmental Conservation (NYSDEC) required the containment of AFFF rinse water and all subsequent stormwater to prevent offsite migration. This was a concern because the stormwater from the site drained into surface water that was being used as a public water supply. NYSDEC would allow our client to resume discharge only once they demonstrated 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, so 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 then reviewed and evaluated the potential migration pathways the contaminated water could take. 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, as well as the cost to install and operate a stormwater carbon treatment system. We then 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. The client recieved a No Further Action within three months of implementing the remedy. Given the difficult nature of perfluorooctane sulfonate (PFOS) – a component of AFFF – a removal remedy was most protective, the fastest, and least costly.
Of the compounds within the PFAS group, PFOS, was resistant to natural reduction. PFOS levels remained elevated in a concentration that was 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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