A river has a total dissolved solids (TDS) concentration that averages Cr = 1200 mg/l, while groundwater recharging the river has a TDS concentration Cg = 300 mg/l. We want to place a water well which will produce 20,000 ft3/day (100 gpm) as close to the river as possible and still meet a water quality limit of c = 500 mg/l TDS. The aquifer is unconfined and has a hydraulic conductivity of 15 ft/day. Before placement of the well, a monitoring well located 1000 ft from the river has a saturated thickness of 65 ft, while the saturated thickness at the river is 60 ft.

Use MAGNET to simulate the groundwater flow  and the water quality dynamics in the mixing zone and use the result to identify the optimal well location. 

MAGNET/Modeling Hints: 

• Use 'Synthetic Mode' to set up your flow model ( 'Other Tools' > 'Utilities' > 'Go to Synthetic Case Area')
• Use the ‘Distance Display’ capabilities when editing geometric features and/or the ‘Ruler’ tool to properly represent distances between model features.
• Represent the stream using a zone feature.