A landfill is leaking an effluent with a concentration of sodium of 1250 mg/L. It seeps into an aquifer with a hydraulic conductivity of 9.8 m/day, a gradient of 0.0040, and an effective porosity of...

A landfill is leaking an effluent with a concentration of sodium of 1250 mg/L. It seeps into an aquifer with a hydraulic conductivity of 9.8 m/day, a gradient of 0.0040, and an effective porosity of 0.25. A downgradient monitoring well is located 25 m from the landfill. What would the sodium concentration be in this monitoring well 300 days after the leak begins? Note: In this problem you will need to find erfc(), which is equal to 1
 erf().