Course Description
The hydraulic analysis of storm drain inlets is a requirement of the design of a storm sewer system that is often overlooked. Significant effort is expended in hydrologic analysis and in sizing the piping system, but inlets are often simply placed in “standard” locations, with little design effort expended. This can result in a storm sewer system that does perform as intended because the runoff is not conveyed into the piping system. This course will cover the basic calculations involved in design of storm drain inlets and provide guidance on appropriate locations and configurations. It will also present information on public domain software that is available to simplify the calculations. Finally, it will present a method to import this information into a software model for the overall storm sewer system.
Course Summary
This engineering continuing education course will provide the user with a basic understanding of how the capacity of inlets can impact storm sewer design. Failure to consider inlet capacity frequently results in an expensive storm sewer system that doesn’t collect nearly as much runoff as anticipated. This course will cover the equations necessary to analyze interception capacity for inlets on a continuous grade and in sags, including grate, curb openings, combination inlets and slotted drains. It will present the basics of using the FHWA software to make the analysis much simpler. It will also present information on how to incorporate the results from inlet analysis into stormwater modeling software, since most software does not explicitly include this information.
Course Outline
I. TYPES OF INLETS:
• Grates
• Curb Openings
• Combination
• Slotted Drains
II. GUTTER FLOW CALCULATION:
• Design Parameters
• Calculation of Top Width and Velocity
III. INLETS ON CONTINUOUS GRADES:
• Splash Over Velocity
• Frontal Flow Interception
• Side Flow Interception
IV. INLETS IN SAGS:
• Weir Flow
• Orifice Flow
V. CURB OPENINGS:
• Length for 100% interception
• Efficiency of small openings
• LID features
VI. USE OF FHWA SOFTWAR
VII. MULTIPLE INLETS
• Continuous grade
• Sag locations
VIII. INLET CLOGGING
IX. INCORPORATING INLETS INTO STORM SEWER MODELS
• Develop relationship between depth and interception
• Develop overflow relationship
• Splitting flow between interception and bypass
Learning Objectives
At the conclusion of this course, the user will:
• Understand the necessary parameters and the equations used to analyze the hydraulic capacity of various inlets on continuous grades
• Understand how to determine the hydraulic capacity of inlets in sags, operating either in orifice flow or in weir flow.
• Understand the basics of the Federal Highway Administration software for inlet calculations.
• Understand how curb cuts used to convey flows to off-street bio-retention cells function.
• Understand how to model inlets in standard storm sewer design software.
Prerequisites:
There are no special prerequisites for this course.
Intended Audience
This course is intended as an introduction to inlet design and therefore the intended audience includes drainage engineers designing storm sewers, transportation engineers involved in roadway projects that include storm sewers and government officials responsible for storm drainage review or plan review.