What is prohibited in casing construction regarding interflow?

The prohibition regarding casing construction involves the placement of perforations that would allow deleterious interflow. This highlights the importance of maintaining water quality and preventing contamination in well operations. Allowing interflow of harmful substances through improperly placed perforations could compromise the integrity of the groundwater system and lead to significant environmental and health risks.

By restricting the placement of perforations that facilitate the movement of unwanted interflow, well contractors help ensure that the groundwater remains protected from pollutants or undesirable water sources. This practice is essential in safeguarding both the well's integrity and the surrounding ecosystem.

The other options involve different aspects of casing construction, such as the design of perforations and sealing methods, which may not directly address the critical concern of preventing contaminants from entering the well through interflow pathways.