Near-source transport of contaminants in heterogeneous media

Waste spills, landfill and storage facility leaks, and recharged surface waters introduce substances over small areas to groundwater.  Resulting substance distributions generally exhibit spatial and temporal variability due to geologic and source property variations.  Knowledge of the transport and fate of contaminants in the subsurface environment is vital to successful groundwater quality management efforts that aim to protect “clean” groundwater and clean up “contaminated” groundwater.  Defining the flow pattern (velocity magnitude and temporal and spatial variations) is key to determining contaminant concentration distributions and rates of movement.

Two problems were investigated:  (1) movement and mixing of a miscible, buoyant liquid plume in flowing groundwater; and (2) mounding, flow pattern, and contaminant distribution of water recharge to a water table aquifer.

The objectives were to: (1) understand and characterize effects of media heterogeneity, transient flow, loading conditions and substance density on the movement and mixing of contaminants for these cases; (2) develop predictive models for these phenomena with steady and transient conditions; and (3) conduct laboratory experiments to determine model parameters and test models.

Regulatory agencies and operators of land disposal facilities who must place and sample monitoring wells for the detection of contaminants will find the results of this project valuable.  In addition, consulting firms involved with spill clean up and determining the impacted area and spreading from the area will benefit from this project’s findings.  Agencies and firms who design and license groundwater recharge facilities and must determine the mounding, penetration, and spreading of the recharged water will also find this research helpful.