PFOS/PFAS Soil Treatability Study, Peterson AFB

Brice Engineering performed a field-scale Treatability Study to evaluate the effectiveness of soil washing for the removal of per- and polyfluoroalkyl substances (PFAS) contamination, specifically perfluorooctane sulfonate (PFOS) and perfluorooctanoic acid (PFOA), from soils derived from Aqueous Film-Forming Foam (AFFF) release sites at Peterson AFB.  The results will be used to evaluate the effectiveness of the soil washing technology in a large-scale application and will help to generate alternative strategies for the EE/CA and subsequent Action Memorandum (AM) for mitigating PFAS contamination in impacted drinking water aquifers at Peterson AFB.

Following a series of bench-scale tests to optimize system design, Brice excavated approximately 500 cubic yards of soil from the area with the highest in situ concentrations of PFOS, the primary contaminant of concern for the site. The soil was placed in a stockpile adjacent to the excavation and homogenized using heavy equipment to ensure relatively uniform particle size distribution and PFAS concentrations for processing through the soil washing plant.  ISM sampling of the stockpile was performed (30 increments, triplicate samples) to establish pre-treatment concentrations of PFAS (e.g, 3.2 mg/kg PFOS). Brice then treated 10 batches of soil through the water-based, closed-loop treatment process to “wash” PFAS from the various soil fractions and capture the mobilized PFAS in GAC and ion exchange resins through treatment of the process water.

A DoD ELAP-certified mobile lab was onsite to provide same- or next-day results to monitor system performance. Brice tested a range of treatment parameters with at least three replicates to statistically determine the optimum parameters for operation and to maximize cost savings. At project completion, the treated soils were approved for backfill into the excavation area.