Evaluating High-Resolution Site Characterisation Tools and Multiphase Modelling to Predict LNAPL Distribution and Mobility

García Rincón, Jonás

Evaluating High-Resolution Site Characterisation Tools and Multiphase Modelling to Predict LNAPL Distribution and Mobility

García Rincón, Jonás

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Publication Type:: Thesis
Issue Date:: 2020

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Field	Value	Language
dc.contributor.author	García Rincón, Jonás
dc.date.accessioned	2020-11-10T22:31:34Z
dc.date.available	2020-11-10T22:31:34Z
dc.date.issued	2020
dc.identifier.uri	http://hdl.handle.net/10453/143873
dc.description	University of Technology Sydney. Faculty of Engineering and Information Technology.	en_AU
dc.description.abstract	Petroleum hydrocarbons in the form of light non-aqueous phase liquids (LNAPLs) are some of the most common subsurface contaminants in urban and industrial environments. LNAPLs may persist in soil and groundwater systems for decades because of their challenging characterisation and remediation. In this research, high-resolution site characterisation (HRSC) tools such as direct-push injection logging (DPIL) and laser-induced fluorescence (LIF) as well as a recently developed multiphase analytical model (LNAPLTRANS) were evaluated in the assessment of LNAPL distribution and mobility. Two field sites from Western Australia (a petrol station site showing seasonal LNAPL confinement in a heterogeneous aquifer–aquitard system and an industrial site with multiple types of LNAPL in a sandy aquifer) were investigated. The variability and most likely values of subsurface parameters required by the models were quantified through field methods, laboratory measurements, and the analysis of previous reports. DPIL, LIF, and LNAPLTRANS were compared to other tools such as LNAPL diagnostic gauge plots, hydraulic testing, coring, and the LDRM model. DPIL allowed rapid collection of comprehensive data sets revealing hydrostratigraphic features overlooked by conventional methods. Predictions of water-saturated hydraulic conductivity were typical of sandy aquifers and not strongly influenced by the presence of LNAPL. The DPIL quantification model could have underestimated the variability of water-saturated hydraulic conductivity according to other field measurements. LIF logging was used to assess LNAPL mobility. LIF response was correlated with LNAPL transmissivity, unlike LNAPL saturation values from coring. Furthermore, LIF logging facilitated the identification of intervals with long-term entrapped and residual LNAPL because of the multi-wavelength waveforms associated with distinct subsurface characteristics. LIF lifetime data and other LIF metrics could improve the delineation of LNAPL-impacted intervals, although non-unique interpretations of HRSC logs may exist. Therefore, investigators should always consider multiple lines of evidence. The application of multiphase analytical models represented a practical way to investigate subsurface scenarios partly accounting for the strong variability of subsurface parameters. LNAPL transmissivity exhibited the largest sensitivity to retention parameters and water-saturated hydraulic conductivity, being also influenced by the relative permeability model. Changes in residual LNAPL saturation affected LNAPLTRANS and LDRM predictions of LNAPL transmissivity in opposite ways. Thus, further research should be conducted on characterisation and modelling of near-immobile LNAPL fractions and retention parameters. Future HRSC approaches should exhibit a more quantitative nature and better integrate scale-appropriate measurements in time and space, eventually resulting in more effective and sustainable management of LNAPL contaminated sites.	en_AU
dc.format	Thesis (PhD)
dc.language.iso	en_US	en_US
dc.relation	https://opus.lib.uts.edu.au/bitstream/10453/143873/2/02whole.pdf
dc.rights	info:eu-repo/semantics/openAccess
dc.rights	The author owns the copyright in this thesis including all reproduction and reuse rights for the work. The work may not be altered without the permission of the copyright owner. Attribution is essential when quoting or paraphrasing from this thesis.
dc.rights	au.edu.uts.lib/ppc
dc.title	Evaluating High-Resolution Site Characterisation Tools and Multiphase Modelling to Predict LNAPL Distribution and Mobility	en_AU
dc.type	Thesis
utslib.copyright.status	open_access	*

Abstract:

Petroleum hydrocarbons in the form of light non-aqueous phase liquids (LNAPLs) are some of the most common subsurface contaminants in urban and industrial environments. LNAPLs may persist in soil and groundwater systems for decades because of their challenging characterisation and remediation. In this research, high-resolution site characterisation (HRSC) tools such as direct-push injection logging (DPIL) and laser-induced fluorescence (LIF) as well as a recently developed multiphase analytical model (LNAPLTRANS) were evaluated in the assessment of LNAPL distribution and mobility. Two field sites from Western Australia (a petrol station site showing seasonal LNAPL confinement in a heterogeneous aquifer–aquitard system and an industrial site with multiple types of LNAPL in a sandy aquifer) were investigated. The variability and most likely values of subsurface parameters required by the models were quantified through field methods, laboratory measurements, and the analysis of previous reports. DPIL, LIF, and LNAPLTRANS were compared to other tools such as LNAPL diagnostic gauge plots, hydraulic testing, coring, and the LDRM model. DPIL allowed rapid collection of comprehensive data sets revealing hydrostratigraphic features overlooked by conventional methods. Predictions of water-saturated hydraulic conductivity were typical of sandy aquifers and not strongly influenced by the presence of LNAPL. The DPIL quantification model could have underestimated the variability of water-saturated hydraulic conductivity according to other field measurements. LIF logging was used to assess LNAPL mobility. LIF response was correlated with LNAPL transmissivity, unlike LNAPL saturation values from coring. Furthermore, LIF logging facilitated the identification of intervals with long-term entrapped and residual LNAPL because of the multi-wavelength waveforms associated with distinct subsurface characteristics. LIF lifetime data and other LIF metrics could improve the delineation of LNAPL-impacted intervals, although non-unique interpretations of HRSC logs may exist. Therefore, investigators should always consider multiple lines of evidence. The application of multiphase analytical models represented a practical way to investigate subsurface scenarios partly accounting for the strong variability of subsurface parameters. LNAPL transmissivity exhibited the largest sensitivity to retention parameters and water-saturated hydraulic conductivity, being also influenced by the relative permeability model. Changes in residual LNAPL saturation affected LNAPLTRANS and LDRM predictions of LNAPL transmissivity in opposite ways. Thus, further research should be conducted on characterisation and modelling of near-immobile LNAPL fractions and retention parameters. Future HRSC approaches should exhibit a more quantitative nature and better integrate scale-appropriate measurements in time and space, eventually resulting in more effective and sustainable management of LNAPL contaminated sites.

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