The correct answer is D. Maximum and minimum flow.
A sewerage system is designed to collect and transport wastewater from homes and businesses to a treatment plant. The system must be able to handle both the maximum flow of wastewater that occurs during peak periods, such as after a heavy rain, and the minimum flow that occurs during off-peak periods.
If the system is not designed to handle the maximum flow, it can overflow, causing sewage to back up into homes and businesses. If the system is not designed to handle the minimum flow, it can become clogged, causing sewage to back up into the system.
Therefore, it is important to design a sewerage system that can handle both the maximum and minimum flow of wastewater.
Here is a brief explanation of each option:
- Option A: Maximum flow only. This option is not correct because the system must also be able to handle the minimum flow of wastewater.
- Option B: Minimum flow only. This option is not correct because the system must also be able to handle the maximum flow of wastewater.
- Option C: Average flow only. This option is not correct because the system must be able to handle both the maximum and minimum flow of wastewater.