Stormwater Treatment Concepts Flashcards
What is integrated stormwater management?
Thinking about all of the factors that somehow affect precipitation as it moves from the land surface to an eventual receiving water. The process of accounting for all factors (rate, volume, quality, ground water impact) in a logical process so that inadvertent mistakes are not made that could eventually harm a resource.
What is the first step in integrated stormwater management?
Determining the scope of the project and the likely solutions that will be needed. If on-site, simple practices will solve the problem, if off-site and impact a regional water body then a broader scale will need to be pursued.
What approach can lead to cost savings and added environmental protection?
Following the fact that low impact development, better site design, and sustainable development are all rooted in the preservation, restoration, and enhancement of the natural drainage system.
Name the steps to the Treatment Train, a multi-BMP approach to managing stormwater.
Pollution prevention, source control, on-site water treatment, regional structure, receiving water.
What are examples of each step of the Treatment Train?
Pollution Prevention - pet ordinances, buffer requirements, public education
Source Control - street sweeping, Illicit Discharge Detection, Elimination
Onsite Stormwater BMPs - rain gardens, permeable pavement
Regional BMPs - constructed pond/wetland, large underground infiltration system
What benefits does a well-developed Treatment Train provide?
Will utilize one or more components that work together to remove pollutants utilizing combinations of hydraulic, physical, biological, and chemical methods. This will ensure management of all pollutants that have been identified as affecting the receiving water.
How does each type of process (hydraulic, physical, biological, or chemical) treat stormwater?
- Hydraulic process to minimize rate of runoff
- Physical process to remove bulk solids
- Physical process to remove settleable solids and floatables
- Physical, Biological, Chemical process to remove suspended and colloidal solids
- Biological, Chemical process to remove colloidal, dissolved, volatile, and pathogens
Give an example of a Treatment Train for a Low Impact Development site.
- Green roof (hydraulic for transpiration/attenuation, biological for plant metabolism)
- Permeable pavement (hydraulic for infiltration, physical for infiltration)
- Bioretention basin (hydraulic for infiltration/transpiration, physical for filtration/sedimentation, biological for plant metabolism/pathogen die-off/nitrification)
- Cistern for irrigation (hydraulic for diversion)
Benefits and disadvantage of Treatment Trains?
Are most effective when they maintain runoff onsite to allow sufficient time for hydraulic, physical, biological, and chemical process to take place. Less effective when a larger catchment area of watershed are used. The highest level of pollutant reduction is achieved in the first BMP implemented.
What does a comprehensive stormwater management system include?
Practices that control the development of runoff, practices that prevent generation of pollutants, practices that remove pollutants before contact with rainfall, BMPs that utilize multiple processes that remove pollutants in stormwater runoff.
What are the 9 factors to evaluate when selecting BMPs?
- investigate pollution prevent opportunities
- design site to minimize runoff, what better site design techniques could be applied
- select temporary construction erosion and sediment control techniques
- identify receiving water issues
- identify climate and terrain factors
- evaluate stormwater treatment suitability
- assess physical feasibility at the site, what are the physical constraints
- investigate community and environmental factors
- determine any site restrictions and setbacks
What can help save space and reduce the cost of structural BMPs?
Using techniques for each of the 9 factors that reduce impervious cover and volume of stormwater runoff at site.
