General well function for soil vapor extraction

• Constant head top boundary added to general well function of Perina and Lee 2006.
• Change of arguments transforms the model to soil vapor extraction from vadose zone.
• Uniform drawdown along screen, specified drawdown or specified flowrate pumping.
• Aquifer: unconfined, confined, leaky, or with overlying reservoir.
• Vadose zone: no cover or leaky cover at the ground surface.

This paper develops a well function applicable to extraction of groundwater or soil vapor from a well under the most common field test conditions. The general well function (Perina and Lee, 2006) [12] is adapted to soil vapor extraction and constant head boundary at the top. For groundwater flow, the general well function now applies to an extraction well of finite diameter with uniform drawdown along the screen, finite-thickness skin, and partially penetrating an unconfined, confined, and leaky aquifer, or an aquifer underneath a reservoir. With a change of arguments, the model applies to soil vapor extraction from a vadose zone with no cover or with leaky cover at the ground surface. The extraction well can operate in specified drawdown (pressure for soil vapor) or specified flowrate mode. Frictional well loss is computed as flow-only dependent component of the drawdown inside the extraction well. In general case, the calculated flow distribution is not proportional to screen length for a multiscreen well.