Environment - Runoff

Methods to Avoid, Minimize, Buffer or Mitigate Highway Runoff Effects

 
Finding cost-effect stormwater treatment technologies that comply with Washington State regulations and the Department of Ecology mandates presents WSDOT with some interesting challenges.

Low Impact Development (LID) - also known as "water conservation design" or "zero impact development" - is one of the technologies WSDOT employs. LID technologies are based on using the cumulative effects of multiple, redundant, decentralized stormwater management techniques to meet stormwater management thresholds. This type of development attempts to control runoff volumes so that end-of-pipe systems are either reduced or entirely eliminated. LID differs from conventional end-of-pipe treatment systems, which are generally used as conveyance systems.

LID uses ten basic design concepts:

1. Minimize impervious areas and high levels of soil compaction when possible
2. Maintain or reduce pre-development runoff curve numbers or runoff coefficients
3. Maximize times of concentration
4. Maintain sheet flow as long as possible in conveyance systems
5. Increase surface roughness
6. Maximize contact with landscaped areas and connecting pervious surfaces
7. Maximize retention of rainfall (increase storage) by amending disturbed soils
8. Flattening grades in impact areas
9. Hydraulically disconnecting impervious areas with receiving waters
10. Connecting pervious surfaces

For linear transportation systems, LID can potentially allow transportation agencies to maximize the use of existing right of ways for stormwater management, reducing the need to acquire more land for stormwater management, and thereby reducing project costs.

Research Proposals

• How can treatment systems be modified to improve dissolved metals removal? (pdf 45 kb)
   
• How can current stormwater treatment system designs be modified to improve their infiltration capacities? (pdf 28 kb)
   
• Are there difficult settings (ferry docks, bridges, etc.) where intensive maintenance and source controls can supplant conventional stormwater treatment systems? (pdf 36 kb)
   
• Are there technical innovations in automobile design that can have measurable, long-term positive effects on highway stormwater quality? (pdf 32 kb)
  
• Which highway runoff BMPs or modifications of existing BMPs are most suitable for treating phosphorus? (pdf 28 kb)
   
• Can fill areas, highway subgrades, and roadsides be used for stormwater storage without presenting significant risk to highways? (pdf 26 kb)
   
• Which oil and spill control methods are most feasible for transportation considering limited maintenance resources?  (pdf 27 kb)