Storm Drain Inlets - Part 3, Capacity of Inlets in Sags

A storm drain system is only as effective as the inlets provided. A very expensive piping system can be rendered very ineffective if the number and capacity of inlets is compromised. While inlets are often placed at intersections as a matter of course, inlets between intersections are often ignored. Inlets provide the means for the runoff from the surface to reach the piping system.

This 1-hour online course (Part 3 of a series) provides a discussion of computations necessary to determine the capacity of types of inlets in sag locations. Part 1 provides a general discussion on types of grates and provides computations for inlet grates. A second course (Part 2) includes curb openings and combination grate and curb openings. A fourth course (Part 4) covers inlet locations and spacing. Another course deals with flow in gutters, which is directly related to inlet capacity.

The student should have an understanding of flow in gutters before taking this course. The text of the course is taken from the Federal Highway Administration¡¯s circular on 'Urban Drainage'. It is strongly recommended that the student take Parts 1 and 2 prior to taking this course and it is also necessary to either take the course on Gutter Flow or have a good understanding of the computations involved in gutter flow.

There will be a multiple-choice quiz at the end of this course.

After completing this course, you will be able to:

• Compute the flow capacity of grate inlets, curb-opening inlets in sag locations.
• Calculate slotted inlets and combination inlets.
•  Describe the impacts of debris clogging on inlets in sag locations.
• Identify appropriate inlet location and spacing.