Characterization and remediation of pathogen, solvent, and petroleum contaminated aquifers

Abstract

This work contains the results of studies of three fluid projects that investigated aspects of groundwater contaminant transport and remediation. The first project performed at Hill Air Force Base in Utah evaluated the performance of a vertical water flushing system for the remediation of a multi-component non-aqueous phase liquid. This project also encompassed determining contaminant distribution through soil core analysis and partitioning tracer studies. The work determined that the limited aqueous solubility of the primary contaminants led to the lack of efficient removal by the vertical water flushing system. The second remediation test evaluated the performance of the solubility enhancing agent cyclodextrin in restoring the contaminated aquifer at Air Force Plant 44 in Tucson, Arizona. The results concluded that this advanced remediation technique was efficient in removing trichloroethene. Further, the project demonstrated the ability to separate TCE from the extracted solution through treatment with an air-stripping system and re-inject it for another multiple flushing of the aquifer. Additional site assessment including determination of lithological and contaminant distribution through well-bore sampling and system optimization by conducting a series of vertical tracer studies. To evaluate the impact of groundwater chemistry and travel distances on the transport behavior of enteric virus, experiments were conducted in the unconfined aquifer at the USGS Cape Cod Research Site. Separate experiments examined the transport behavior of bromide (Br-) and the bacteriophage PRD-1 in the effluent plume and the shallower uncontaminated groundwater. Results indicated the vast majority of the bacteriophages were lost from solution upon injection. The results further showed that this initial loss occurred within the first meter for the uncontaminated zone, whereas it occurred over a 4-meter distance in the contaminated zone. The greater distance required for the contaminated zone to defect similar mass loss is attributed to anion-exchange competition by organic matter, phosphate, and other anions present in higher concentrations in the contaminated zone. The results of this study indicate that a small, but infectious fraction of viable virus particles can persist and travel significant distances in sedimentary aquifers, despite variability in water chemistry.