Oral Presentation Australasian Groundwater Conference 2017

LNAPL dynamics in the subsurface: linking multi-phase and multi-component processes  (113)

Kaveh Sookhak Lari 1 , Greg B Davis 1 , John L Rayner 1
  1. CSIRO, Floreat, WESTERN AUSTRALIA, Australia

We aim here to highlight recent advances in linking multi-phase and multi-component processes in a modelling framework to track natural behaviours and remediation strategies for light non-aqueous phase liquid (LNAPL) groundwater contamination problems. LNAPLs, such as petroleum fuels, travel as a separate phase relative to water, air and soil, but also consist of thousands of compounds that partition and pose risks to each of these phases and domains.  Our intention is to elucidate how multi-phase and multi-component modelling helps better understand the short and long term fate and risks of LNAPL contamination in subsurface media.

We determined and updated a modelling platform to incorporate key attributes and conceptual understanding. Short and long term simulations were undertaken of spill releases, along with comparison of model outputs against field data from active gasoline recovery options. A hysteretic feature was embedded. 

The simulations show the criticality of linking multiphase and multicomponent features for LNAPLs. The platform also indicated the importance of hysteretic behaviour in determining LNAPL component partitioning. Release scenarios allow assessment of likely medium to long term distributions and compositional changes as LNAPL product migrates through the vadose zone to groundwater.  The framework was able to mimic product recovery data from a field trial, validating its main features.

A multi-phase and multi-component modelling framework has been validated for assessment of LNAPL groundwater contamination risks. Short and longer term simulations have elucidated key understandings and the code has been validated for LNAPL product recovery scenarios. This is key to improved estimation of endpoints associated with different remediation techniques. It can also provide information about changing LNAPL composition and risks over time.  

  1. Sookhak Lari, K. and Davis, G. B. and Johnston, C. D. 2016. Incorporating hysteresis in a multi-phase multi-component NAPL modelling framework; a multi-component LNAPL gasoline example. Advances in Water Resources. Vol. 96. pp. 190-201
  2. Sookhak Lari, K. and Johnston, C. D. and Davis, G. B. 2016. Gasoline Multiphase and Multicomponent Partitioning in the Vadose Zone: Dynamics and Risk Longevity. Vadose Zone Journal. Vol. 15. Issue 3. pp.-15.
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