Which of the following is NOT a factor that should prevent the construction of a leaching system?

The factor that should not prevent the construction of a leaching system is dry sandy soil. Sandy soil has excellent drainage characteristics, allowing for rapid permeability and reducing the likelihood of water pooling or flooding. This is beneficial for leaching systems because it helps to ensure waste effluent can disperse properly into the soil without becoming saturated.

In contrast, high groundwater levels, surface flooding, and ledge rock are significant concerns when considering the construction of a leaching system. High groundwater levels can compromise the effectiveness of the leach field, as effluent would not be able to disperse adequately if the surrounding soil is already saturated with water. Surface flooding can lead to the same issues; if the area is prone to flooding, it can inundate the leaching system which undermines its function and risks contamination of the surrounding environment. Ledge rock presents physical challenges and can limit the depth to which the leaching system can be installed, potentially creating drainage issues.

Thus, dry sandy soil is an advantageous condition for leaching systems, promoting efficient drainage and mitigating the risks associated with wastewater management.