Michael J Deliz | Search NASA

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PFAS Treatment Pilot Study using Granular Activated Carbon at Kennedy Space Center, Florida

Per- and polyfluoroalkyl substances (PFAS) have been found in investigative derived waste (IDW) generated from groundwater sampling and remediation activities conducted at Kennedy Space Center (KSC), Florida. PFAS are exceptionally strong compounds because of carbon-fluorine bonds resulting in resistance to degradation, low chemical reactivity, compound stability, and persistence in the environment. The regulatory status of PFAS is very dynamic. PFAS is not considered a hazardous waste and has no federal or state (Florida) cleanup requirements at this time. Due to the current and unknown future of the regulatory and treatment landscape, non-hazardous IDW, based upon site volatile organic compounds (VOCs) regulated under Title 40 of Federal Regulations part 261, containing PFAS is not being processed for off-site waste disposal under KSC’s Resource Conservation and Recovery Act permit as a proactive precaution. Long-term storage of aqueous IDW in the meantime was determined to be inadequate due to the potential for spills and/or leaks. A very limited number treatment methods are available at this time. To date, granular activated carbon (GAC) and ion exchange technologies have been found to be some of the most consistent treatment options for removing PFAS from aqueous media. Therefore, a pilot study using GAC was developed at KSC to determine the feasibility of treating non-hazardous IDW containing PFAS to reduce the total volume of PFAS waste and minimize the risk of leaks or spills while storing the waste until complete PFAS-destructive treatment options are more readily available. NASA wanted the pilot test to be able to demonstrate the ability to completely remove 18 PFAS compounds and the site VOCs to below the state of Florida groundwater cleanup target levels (GCTLs).

Michael J Deliz↗

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Air Sparge Pilot Study in the DNAPL Source Zone at Launch Complex 34

Multiple releases of trichloroethene (TCE) occurred at Launch Complex 34 (LC34) between the late 1950s and 1968. A 2007 conceptual site model estimated a 2-acre dense non-aqueous phase liquid (DNAPL) source area with mass in excess of 90,000 pounds, nearly 40 years after termination of launch activities. Located on a barrier island, LC34 currently has no complete exposure pathways and a historical groundwater flow radial from the DNAPL source zone (DSZ), the focus area of this study. The geology at LC34 is classified as Layers 1 through 9 with each layer representing a different lithology. These lithologies contribute to large variations in hydraulic conductivity (1x10-3 cm/sec to 1x10-8 cm/sec) with notable fine-grained units at Layer 4 (sandy clay) and Layer 7 (fine silty sand). Historically, technologies implemented at LC34 have been split vertically based on technology limitations and lithology. Remedial technologies have been evaluated to control and/or remediate the DSZ in the past; however, more aggressive technologies required significant cost and would likely leave considerable mass. Thus, an adaptive site management strategy has been implemented that adopts a treatment train approach which began in 2009 with hydraulic containment via pump and treat to control mass discharge from the DSZ while removing mass as a secondary benefit. Concurrently, hot spot areas in the larger dissolved plume are being treated by air sparging to reduce overall mass and the plume footprint. In 2019, a re-characterization of the DSZ was completed to update conditions in support of implementing more aggressive technologies as part of the treatment train approach. The results showed that the DSZ remained relatively the same size but with a slightly different morphology. Moreover, data showed that the fine-grained units (Layers 4 and 7) are storing most of the remaining mass, with TCE concentrations suggestive of DNAPL extending into Layer 7 (approximately 80 to 100 ft below land surface). Based on the current conditions, more aggressive technologies are still cost prohibitive; therefore, a different approach is warranted to determine the next implementable step in the treatment train. Air sparging is being proposed as a technology alternative based on several factors including lower treatment costs. A pilot study was conducted to test the feasibility of air sparging in the DSZ as the next step in the treatment train for that area.

Launch Complex 34↗