Which of the following is not a consideration when selecting a screen for a monitoring well?

• A. Type of well head seal
• B. Screen slot size
• C. Formation permeability
• D. Depth to groundwater

Answer: (A)

Screen selection for a monitoring well is guided by how the aquifer behaves and how the screen will admit groundwater while keeping sediments out. The key design factors are the formation's permeability and the slot size of the screen, along with material and length to match the well's objectives and prevent clogging or sand intrusion. The type of well head seal is not part of this design process because it deals with surface hardware that seals the top of the casing, not with how the screen interacts with the subsurface environment.

Depth to groundwater doesn’t change the fundamental screen design parameters like slot size or screen length; it mainly influences where you place the screen to stay within the saturated zone. In contrast, formation permeability and slot size directly determine how easily water enters the well and how much sediment might enter, which is why they are considered essential in choosing a screen.