A waste stabilization pond following a septic tank must allow for volume how many times the average daily flow?

The correct answer, which indicates that a waste stabilization pond following a septic tank must allow for a volume of 60 times the average daily flow, is based on the design requirements set forth for effective wastewater treatment.

Waste stabilization ponds are designed to provide adequate time for the treatment processes, including sedimentation, biological treatment, and disinfection, to occur effectively. The requirement of 60 times the average daily flow ensures that there is sufficient volume to accommodate variations in flow and loading, while allowing for the natural processes that break down organic materials and pathogens in the wastewater.

This volume also allows for periods of low flow, which can occur due to seasonal variations in water usage, ensuring that the pond remains effective over the long term. Having this significant capacity helps to maintain a stable environment for the primary treatment microorganisms, thereby enhancing the overall efficiency of the treatment system.