INSTRUCTOR: Mark Peterson, P.E.

Purpose and Background

Low Impact Development (LID) techniques are being used extensively for storm water controls. Most LID techniques are designed to attempt to replicate the original hydrology of a site. They are also sometimes promoted as a way to significantly reduce the storm sewer system required for a development. But do they actually meet these requirements? If so, as engineers, how can we verify that we can meet these goals?

In order to verify how LID features function, it is necessary to examine in more detail the hydrologic calculations associated with these techniques. In many LID designs, the intent is to capture and store or infiltrate 80% or 90% of the annual rainfall. This course will cover the methods of analysis to determine the design rainfall, including a brief example of the statistical analysis required. The course will also cover the use of the EPA SWMM software to determine if the proposed LID features will actually capture the required amount of annual rainfall, including longer-term simulations that are often required. It will also cover how to meet the Stormwater Runoff Requirements for Federal Projects under Section 438 of the EISA.

The hydraulic design of LID features is often neglected. The assumption is often made that all of the water goes into the LID feature simply because that is the design intent. A good hydraulic design is necessary based on the configuration of the LED feature. This course will cover hydraulic analysis of numerous LID features, including structures intended to divert water into LID features. It will also examine how the use of LID features impacts the required sizing of storm sewer systems.

Low Impact Development techniques have the potential to significantly change how we approach storm water design. However, if the hydrology and hydraulics of these features are not carefully considered by the designers, these features also have the potential to be very ineffective and promote inappropriate design of future storm sewer systems.

Seminar Benefits

• Understand how rainfall data is used to develop the 80% event
• Understand what field measurements are necessary to estimate the performance of a bioretention cell
• Learn how to model infiltration and runoff from bioretention cells using the EPA SWMM software
• Learn how to estimate the potential capacity of infiltration trenches
• Learn how to model permeable pavement options using the EPA SWMM software
• Understand how LID features can impact peak flow calculations
• Learn how to improve the performance of LID features including bioretention cells and infiltration trenches

Learning Outcomes

• Use data available from the Weather Service to estimate appropriate rainfall factors for LID features
• Determine the hydrologic and hydraulic performance of bioretention cells
• Determine how to model infiltration and permeable pavement features using common software
• Determine how improvements to specific hydraulic features can improve performance

Assessment of Learning Outcomes

Learning objectives are achieved through case studies, class problems, classroom discussion, a short post-test.

Who Should Attend?

This course is for anyone involved with the design or review of Low Impact Development (LID) features. This includes design engineers, regulatory officials and landscape architects. The course is technical in nature but the equations used are not complicated. Participants should bring a calculator for the problem solving exercises.

Seminar Outline

TIME:  8:30 a.m. - 4:30 p.m.

DAY 1

• Introduction and Welcome
• Overview of LID features
• Sources of rainfall data required for LID analysis
• Use of rainfall data to create appropriate storms for LID analysis
• Hydrologic and hydraulic analysis of bioretention cells
• Hydrologic and hydraulic analysis of vegetative swales

DAY 2

• Hydrologic and hydraulic analysis of infiltration trenches
• Hydrologic and hydraulic analysis of pervious pavements
• Analysis of long-term LID performance
• Analysis of LID impacts on peak flows
• Improving performance of LID features

Hotel Information

Discounted hotel rooms are available on a first-come, first-served basis. See discount deadline and rates below.