Combination Inlet

HEC-22 distinguishes two cases:

• The grate and the curb opening are placed side by side. In this case, the flow interception by the curb opening is negligible, and the capacity of the combination inlet is identical to that of the grate alone.
• The curb opening is extended upstream of the grate in order to intercept debris that could otherwise clog the grate inlet. The flow intercepted by the combination inlet is calculated as the flow intercepted by the curb opening upstream of the grate inlet, plus the portion of the remaining flow intercepted by the grate.