Stormwater Treatment for Highway Projects

1. Stormwater Treatment for Highway Projects Regulatory Drivers, Management Criteria, and the Role of Roadway William Fletcher Water Resources Program Coordinator

2. The regulatory environment has gotten stricter • Highway runoff adds pollutants to our streams and rivers • Salmon and other fish are suffering from the effects of water pollution

3. DEQ • Clean Water Act Sect. 401 Water Quality Certification: Project specific approval when a 404 permit is needed • NPDES MS4 permit: ODOT commits to treating its stormwater • TMDLs and 303(d) listed streams: ODOT must have and implement a plan to reduce these pollutants.

4. NMFS and USFWS Endangered Species Act: Stormwater treatment required and reviewed on a project basis if T&E fish are affected

5. Stormwater Management is Needed For any action that will • Add impervious surface area • Change the drainage (type, location etc.) • Replace or widen stream crossing structures • Require a CWA 404 permit and involves impervious surface

6. When is Stormwater Management not an issue? • Paving, grindout and inlay, with no increase in impervious surface • Minor actions: pads for signs etc.

7. Water Quality Goals Treat all of the highway runoff from the Contributing Impervious Area generated by the Water Quality Design Storm using Preferred BMPs

8. Contributing Impervious Area The “Contributing Impervious Area” (CIA) consists of all impervious surface within the strict project limits, plus impervious surface owned or operated by ODOT outside the project limits that drain to the project via direct flow or discrete conveyance

9. Contributing Impervious Area project limits CIA non-CIA

10. CIA Boundaries project limits

11. Water Quality Design Storm Defined for each Climate Region Percentage of the 2 year 24 hour storm: 50% 67% 75%

12. Flow Control Design Storms Maintain the frequency and duration of discharges from the range of Flow Control (Water Quantity) Design Storms to protect channel form and process

13. Preferred BMPS • Infiltration techniques • Bioretention facilities • Bioslope (“Ecology Embankment”) • Amended Soil Swales and Filter Strips • Treatment wetlands

14. Low Impact Development Water quality features in the linear right- of-way that emphasis infiltration and filtration through vegetation

15. Low Impact Development • Compost blankets on side slopes • Flat bottomed, vegetated roadside ditches with amended soil beds • Ecology Embankments (bio-slopes)

16. Stormwater In Project Development Stormwater can no longer be an afterthought in project development and design

17. Baseline: • Roadway: Identify features that may affect selection of treatment options • Water Resources Specialist: Identify water resources issues

18. Conceptual Site Layout: • Roadway: Identify and incorporate LID techniques • WRS: Evaluate extent WQ goals are met by the LID techniques, identify additional treatment requirements to be addressed by the Stormwater Engineer

19. DAP • Roadway and WRS: Input on the final selection of the stormwater management techniques • Stormwater Engineer (if needed): Evaluation of Engineered BMPs • Project Team: Selection of treatment BMPs (LID and Engineered) and incorporation into DAP

20. Advance Plans and Beyond • Roadway: Stormwater design if Engineered BMPs not needed • Stormwater Engineer: Design of Engineered BMPs • WRS: Assemble Stormwater Management Plan for Environmental Permitting

21. QUESTIONS?