Oral Presentation Australasian Groundwater Conference 2017

Predicting the potential recovery of petroleum fuels from impacted aquifers (182)

Robert J Lenhard 1 2 , John L Rayner 1 2 , Greg B Davis 1 2
  1. CSIRO, Wembley, WA, Australia
  2. Cooperative Research Centre for Contamination Assessment and Remediation of the Environment (CRC CARE), Callaghan, NSW, Australia

Contamination of groundwater by petroleum fuels can harm human health and the environment. To help reduce the potential harmful impacts, the petroleum fuels are pumped from wells to the surface for disposal or reuse. This is commonly referred to as petroleum fuel recovery. The design of cost-effective petroleum fuel recovery activities depends on assessing the subsurface volume of the petroleum fuels and the rate at which they may migrate toward recovery wells. Besides assessing the total petroleum fuel volume in the subsurface, it is important to determine the distribution of petroleum fuel that is mobile and can migrate to wells in reasonable time periods. Additionally, assessing the immobile petroleum fuel volume entrapped by water and the petroleum fuel volume that is relatively immobile above the water table (i.e., residual) also is important for longevity and risk assessment. To help bring science to practice for petroleum fuel remediation, a model was developed to predict the free, residual, and entrapped petroleum fuel volumes in a vertical slice of the subsurface based on current petroleum fuel levels in wells and historic water table fluctuations. The model predicts elevation-dependent free, residual, and entrapped petroleum fuel saturations from the aqueous and petroleum fuel liquid pressures as reflected by the liquid levels in wells at hydrostatic conditions. Further, the model predicts elevation-dependent petroleum fuel relative permeabilities for the free petroleum fuel from the free, residual, and entrapped petroleum fuel saturations. Integration of the saturations and relative permeabilities over a vertical slice of the subsurface yields petroleum fuel volumes and transmissivity. Presented results show model predictions for several hypothetical scenarios. The model is potentially valuable for designing cost-effective petroleum fuel operations and understanding limitations of petroleum fuel recovery from the subsurface.

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