What is the height specification for the inflow dike in relation to the pipe diameter?

The height specification for the inflow dike being equal to the pipe diameter plus 6 inches is based on ensuring adequate hydraulic performance and preventing erosion around the inlet of the pipe. This additional height provides a buffer that is crucial for managing water flow effectively.

By incorporating a height that exceeds the pipe diameter, the design accommodates for varying stormwater flows and sediment levels, preventing undercutting and failures around the pipe entrance. It also helps in maintaining positive drainage and avoiding backflow, which could compromise the system's efficiency.

In scenarios where the inflow dike is not sufficiently high, there is an increased risk of water overtopping the dike during heavy rainfall events or rapid runoff, potentially leading to erosion and sedimentation issues. Therefore, the specification of 6 inches above the pipe diameter is a prudent design choice grounded in principles of hydraulic engineering and erosion control.