The bottom of a subsurface field and each trench must be level to what tolerance?

The requirement for the bottom of a subsurface field and each trench to be level within a tolerance of +/- 1 inch is crucial for the effective functioning of a private sewage system. Maintaining this tolerance ensures that wastewater flows evenly through the system, preventing issues such as pooling or backing up, which can lead to system failure or contamination.

At a tolerance of plus or minus 1 inch, the system can better accommodate for variations in soil and topography while still promoting adequate drainage and aeration. This is important as the design and function of the drainage field depend on maintaining consistent flow and preventing excessive saturation. A tighter tolerance, such as +/- 0.5 inches, might be impractical in many field conditions, while looser tolerances like +/- 2 inches or more could compromise the efficiency and longevity of the sewage system.

Therefore, a tolerance of +/- 1 inch strikes a balance between manageable installation conditions and optimal operational efficiency in subsurface sewage treatment systems.