Course Description:
Stormwater runoff in urban and developing areas is one of the leading sources of water pollution in the United States. EPA has developed guidance to provide a step-by-step framework that will help engineers working on projects maintain pre-development site hydrology by retaining rainfall on-sit through infiltration, evaporation/transpiration and re-use. This course provides background information, case studies and guidance on maintaining pre-development hydrology. This can be accomplished using a variety of stormwater management practices referred to as Low Impact Development (LID) techniques. They are also sometimes referred to as green infrastructure, and include for example, reducing impervious surfaces, using vegetative practices, porous pavements, cisterns and green roofs. These practices can help protect and restore water quality. These practices can also reduce site runoff volumes.
Course Outline:
PART 1 – IMPLEMENTATION AND FRAMEWORK
A. Background
B. Benefits and outcomes of the new stormwater performance requirements
C. Applicability and definitions
D. Tools to implement the requirements of Section 438
1. Option 1 – Retain the 95th Percentile Rainfall Event
2. Option 2 – Site Specific Hydrologic Analysis
E Calculating the 95th percentile rainfall event
PART 2 – CASE STUDIES
A Introduction
B. Runoff Methodology Parameter Assumption
1. On-site Stormwater Management Practice Determinations
C. Bioretention areas
D. Porous/permeable pavements
E. Cistern
F. Green roof
1. General Approach
2. Methods for Determining Runoff Volume
3. Case Studies
Learning Objective:
At the conclusion of this course, the user will:
• Understand the meaning of the 95th percentile rainfall event and know how to calculate it.
• Understand how the Stormwater Runoff Requirements for Federal Projects can be met.
• Understand how LID features can be used to retain the 95th percentile event
• Understand how LID features can be used to mitigate the impacts of the 95th percentile event when the entire runoff cannot be retained.
• Understand how LID features including bioretention areas, porous pavements, cisterns and green roofs can be used to mitigate stormwater impacts
• Understand how to determine the runoff volume from an event, rather than just the peak flow
Prerequisites:
There are no special prerequisites for this course.
Intended Audience
This course is intended to cover the process that is recommended to determine appropriate use of LID components. While it is based on guidance for federal facilities, the process is equally applicable to any LID design. Therefore the intended audience includes all engineers working in the storm water field. It also includes engineers and managers whose work includes some aspect of storm water or water quality as a basic understanding of the LID concepts and process can aid in project coordination.
Course Summary:
This course will provide the user with a basic understanding of the process to evaluate the use of LID features to mitigate impacts of development. The course will also provide the necessary information to calculate the 95th percentile rainfall event for any location. It covers a comprehensive approach to evaluation of the necessary runoff volumes that need to be stored and how to evaluate the effectiveness of a number of LID features.
