Product(s):	StormCAD, SewerCAD, SewerGEMS, CivilStorm, OpenRoads Designer, OpenSite Designer
Version(s):	24.00.03.23 and higher (OpenFlows) and 25.00.00.184 and higher (OpenRoads/OpenSite)
Area:	Calculations

 

Problem

When using catalog inlets, will the calculations consider the HEC-22 4th Edition standard methodology?

Solution

Generally speaking, catalog inlets (curb, grate, combination, slot, etc) use the HEC-22 standard equations for calculating capture efficiency, spread and depth. See: HEC-22 Inlet Capacity Calculations

The fourth edition of the HEC-22 manual references FHWA's "TECHNOTE: Curb-Opening Inlet Interception on Grade" (FHWA-HRT-22-061). If you need to adopt this updated procedure instead of the standard HEC-22 calculations for curb inlets on grade, select "True" for the Calculation Option "Use 2022 TECHNOTE for Curb Inlets on Grade" (Analysis > Options):

Note: this calculation option was introduced in version 24.00.03.23 of the OpenFlows Storm and Sewer products, and version 25.00.00.184 of OpenRoads and OpenSite. It is available with the GVF-Rational, GVF-Convex, and Explicit solvers.

For information on the Technote, see this article from the FHWA.