This problem considers the movement of a benzene plume in a stochastically stratified confined aquifer. The  plume is moving towards a lake that is used for recreation and drinking water supply. This concerns the local municipality - the long-term health effects of long-term exposure above the Maximum Contaminant Level (MCL) of 0.005 mg/L is known to cause anemia, decrease in blood platelets, and increased risk of cancer.

Assess the risk, or probability of the contaminant concentration exceeding the MCL at the aquifer-lake interface. Use MAGNET to generate the stochastically stratified K field. You should calculate the risk for different times. Assume that t=0 coincides with the initial position of the plume at the monitoring well, as depicted in the graphic below. You may also assume that the horizontal scale is 100 times larger than the vertical scale (i.e., the aquifer is essentially "perfectly stratified").

Analysis of detailed borehole data yielded the following useful information:  

• Mean hydraulic conductivity 10.7 m/d
• LnK variance: 1.8
• Vertical correlation scale: 6m
• effective porosity: 0.15

MAGNET/Modeling Hints:

• Use ‘Synthetic mode’ in MAGNET to create a model domain.
•  Add prescribed head line and zone features along the left and right edges to represent the head measured at the monitoring well and lake, respectively.
•  Use a zone feature of the entire aquifer area to assign the hydraulic conductivity as a random field realization.
•  Add a monitoring well at the aquifer-lake interface to track concentrations as the simulation proceeds.
•  Analyze the plots and charts using the DisplayCharts tool ( 'Analysis Tools' > 'Analysis' > 'Display Charts' )