How deep should the invert of the opening between compartments be relative to the liquid depth?

The correct understanding of the positioning of the invert of the opening between compartments in a septic system is crucial for effective wastewater treatment. The specification that the invert should be placed 40% below the liquid depth ensures that the flow between compartments happens efficiently without risking the disturbances of settled solids or scum layers in the first compartment.

By placing the invert at this specific depth, you encourage the movement of liquid while providing a barrier that prevents solids from easily flowing into the next compartment, which is vital for proper treatment and separation processes. This placement helps maintain the appropriate hydraulic conditions necessary for the system's proper functioning. It’s important to adhere to these guidelines to avoid issues related to the effluent quality and overall septic system performance.

Understanding the rationale behind the specific depth requirements can also aid in maintaining compliance with local regulations and ensuring the longevity of the system.