Stormwater Management (BMPs Part 2) Flashcards
What is Stormwater Management?
Managing rainfall runoff using conventional storm-based approaches to sizing and designing drainage facilities
What are some issues with the traditional approach to having stormwater go into pipes?
- Runoff volumes have increased with urbanization, thereby costing more as it goes to treatment systems
- Large storms can result in combined sewer overflows (CSOs)
- Most importantly, traditional systems have altered the natural hydrologic path of water flow
What are effects of altering the natural hydrologic pathway?
- Groundwater isn’t recharged
- Soil moisture decreases
- Aquifers shrink
- Slow water recharge during dry periods is decreased
What does ADAPT stand for? (Guiding Principles for Stormwater Management)
A gree that stormwater is a resource
D esign for the complete spectrum of rainfall events
A ct of a priority basis in at-risk drainage catchments
P lan at four scales - regional, watershed, neighbourhood & site
T est solutions and reduce costs by adaptive management
What are the three C’s for managing rainfall events?
Capture small, frequent storms
Control and reduce runoff from large storms
Convey extreme events
What is Grey vs. Green Stormwater Infrastructure?
Green: Captures rainwater and naturally treats or removes urban pollutants and returns rainfall to natural hydrologic pathway
Grey: traditional piping infrasturcture designed to quickly transfer runoff flows to discharge areas
What % runoff should stormwater systems target to replicate?
Natural systems have 10% runoff from rain
How does a sytem achieve Green Stormwater?
- Disconnect impervious areas from drainage system
- Runoff can flow from impervious area into green systems first
- When green systems are overwhelmed, flow can use grey systems
What are some major types of Green control systems in the GVRD?
- Absorbent landscapes
- Vegetates swales
- Bioretention facilities
- Pervious paving
- Infiltration trenches
- Extensive green roofs
- Rainwater harvesting
- Water quality Structures
- Detention Tanks and Ponds
- Constructed Wetlands
What is Absorbent Landscaping?
Soaks up, stores and slowly releases rainfall.
Mimics natural undisturbed areas
What is a Vegetated Swale?
- Shallow grassed or planted channels
- Stores the design storm, allowing it to infiltrate slowly
What are three infiltration methods? (For Swales)
- Full infiltration
- Full infiltration with reservoir
- Partial infiltration with reservoir and subdrain
What is a Bioretention facility?
Concave landscaped area where runoff is collected and allowed to infiltrate
What is Pervious Paving?
Surface layer of paving stones or appropriate vegetation allowing rainfall to percolate into the ground
What is an Infiltration Trench?
Underground trench or reservoir that allows storage of water until it infiltrates into the ground
