a) A pool of Tetrachloroethylene (PCE) has formed above a vertical fracture of circular cross section having an average diameter, D, of 2 mm. Water pressure conditions in the fracture and the overlying aquifer are hydrostatic. Estimate the height of the PCE pool, Hc that must form above the fracture entrance before DNAPL invasion of the fracture takes place.
b) If the fracture were planar in shape, having an average opening of 2 mm, what would the new value of Hc be?