1. Monitoring Roadway Runoff and Development of a Design Guide for Roadway BMPs John Stansbury, Ph.D., P.E.Massoum Moussavi, Ph.D., P.E., and Tian Zhang, Ph.D., P.E.

2. Outline Introduction Field Study BMP Design Guide Summary

3. Regulatory Background Clean Water Act (CWA, 1972): requires NPDES permit (National Pollutant Discharge Elimination System). Municipal Separate Storm Sewer System (MS4) discharges/regulation: MS4 defined as: A system of conveyances owned/operated by a public body. Designed or used for collecting or conveying stormwater. Not a combined sewer & not part of a POTW. MS4s discharges are regulated nonpoint source pollution. MS4s regulation is part of the CWA (1987 amended): Phase I (passed in 1990): requires MS4s to submit Storm Water Pollution Prevention Plans (SWPPP) to the US EPA. Phase II (passed in 1999): requires 6 minimum BMPs. The objective of MS4s is to reduce pollutant effluents to the Maximum Extent Practicable (MEP) (so not linked with numeric limits).

4. Regulatory Background NDOR is a non-traditional MS4 and is required to manage roadway runoff pollution within MS4 boundaries. NDOR is required (by NDEQ): To capture/treat the first 0.5 Water Quality Volume (WQV) that runs off of any new/redeveloped impervious area. Currently treatment levels are only required to be the Maximum Extent Practicable (MEP).

5. Project Objectives Determine water quality of runoff. Evaluate performance of the existing BMPs. Improve design guidelines of treatment BMPs.

6. Field Study Location and six sub-basins Methods: Flow Measurement Sampling Sites Sample Analysis Results

7. Location Intersection between I-80 and I-680 in Omaha, Nebraska

8. Sub-basins and SamplingPorts

9. Sub-basin 1: ConstructionDebris Lot

10. Sub-basin 2: Ditch

11. Sub-basin 3: West PipeTributary Area

12. Sub-basin 4: Grass Strip alongI-80

13. Sub-basin 5: East PipeTributary Area

14. Sub-basin 6: Detention Basin

15. Flow Measurement Construction debris lot: Rectangular weir Ditch: V-notch weir West, east and basin outlet pipes: AV (area velocity) flow modules and sensors

16. Sampling Sites A and BSite A: Construction debris lot inlet Site B: Ditch toward 108th Street

17. Sampling Sites C and D Site C: Northwest outlet Site D: Northeast outlet

18. Sampling Site E Site E: Detention basin outlet

19. Sampling Protocol Storm identification: The Weather channel website NOAA website AccuWeather website Weather Underground website Grab (first flush) and composite (event mean) samples

20. Hydrologic Model HEC-HMS 3.4 Eight sub-basins Hydrographs for each sampling point Flows used in the compositing process

21. Chemical/Biological Analysis Heavy metals Petroleum hydrocarbons BTEX PAHs Road salts Total suspended solids Total dissolved solids BOD and COD.

22. Results Arithmetic Mean and Median for First Flush and Event Mean Concentrations for Site A for All Sampled Events

23. Comparison with Similar Studies

24. Results Metals (Cu, Cd, and Zn), COD, TSS, & TDS are the major contaminants found in the highway runoff. SVOCs and VOCs were below the detection limits. A weak correlation between concentrations, TSS, antecedent dry period (ADP), total rainfall, and volume of runoff. Roadside vegetation (site B) is very efficient to reduce runoff/pollution via infiltration. The existing BMP (detention pond) seems to be somewhat effective in reducing heavy metals, chloride, COD and TSS loads.

25. BMP Design Manual Introduction to BMPs NDOR Chapter 3 Design Guide

26. Introduction to BMPsBMPs defined as: schedules of activities prohibitions of practices maintenance procedures structural and/or managerial practices that, when used singly or in combination, prevent or reduce the release of pollutants to waters of the US.Six minimum BMPs (control measures) identified by CWA: Public participation and involvement Public education and outreach Illicit discharge Construction site storm water runoff control Post-construction storm water runoff control Municipal operations pollution prevention and good housekeeping

27. NE Stormwater ManagementProgram

28. Chapter 3: Post ConstructionStormwater Control Treatment BMPs include: Permanent structural BMPs, such as: Settling of particulate matter Filtration Biological uptake Soil adsorption Non-structural BMPs for source control such as policies/ordinances that: Provide requirements and standards Protect sensitive areas (wetlands and riparian areas) Maintain/increase open space Provide buffers along sensitive water bodies Minimize impervious surfaces Minimize disturbance of soils and vegetation

29. Remediation Techniques Primary BMPs Vegetated Filter Strips Vegetated Swales Bioretention Sand Filter Horizontal Filter

30. Guidance Manual Format Fact Sheets Pollutant removal potential Construction and maintenance costs Siting constraints Maintenance operation Design Guides Design criteria Design process Example

31. Vegetated Filter Strip Design Criteria WQV flow depth < 1 inch WQV velocity below < 1 ft/s Slopes in flow direction from 215% Minimum 15 foot flow path 80% Vegetated Cover

32. Bioretention Design Criteria Media: compositions depending on needs Can be designed as infiltration Flexible layout

33. Horizontal Filter DesignCriteria Media filled trench in ditch bottom Temporarily store WQV in media Cobble armoring (1ft above flow depth)

34. Project Overview Three-year project (July 2008March 2011) Six events sampled each year. Two samples in spring, summer, and fall seasons Total: 12 storms for sampling sites A, C, D, and E 10 for site B Data analysis Development of design manual

35. Summary Metals (Cu, Cd, and Zn), COD, TSS, & TDS were the major contaminants found in the highway runoff. SVOCs and VOCs were below the detection limits. There was a weak correlation between concentrations, TSS, antecedent dry period (ADP), total rainfall, and volume of runoff. Roadside vegetation (site B) was very efficient in reducing runoff/pollution via infiltration. The existing BMP (detention pond) seems to be somewhat effective in reducing heavy metals, chloride, COD, and TSS loads. Effectiveness of different BMPs needs to be evaluated. BMP design is case sensitive, but development of general design procedures is possible.

36. Summary NDOR defines priority stormwater outfalls as: Concentrated stormwater flow locations directly discharging from state ROW to the following: Streams (Perennial and Intermittent)/Lakes/Wetlands/MS4s Ephemeral drainage that directly discharges to one of the above within 500 feet beyond the ROW line

37. Chapter 3: Post constructionStormwater Control Responsibility: Treatment of first of runoff (first flush). Runon New Development BMPs selection criteria (NDOR): Primary treatment: 80% removal TSS Metals are secondary treatment concern Low maintenance Cost Effective No open water Implement BMP within existing right of way as much as possible Infiltration should not be a primary removal mechanism near roadway Aesthetics

38. Summary of Sub-basins

39. Results Arithmetic Mean and Median for First Flush and Event Mean Concentrations for Site C for all Sampled Events

40. Results Arithmetic Mean and Median for First Flush and Event Mean Concentrations for Site E for all Sampled Events

41. Results Arithmetic Mean and Median for First Flush and Event Mean Concentrations for Site C for all Sampled Events

42. Results Arithmetic Mean and Median for First Flush and Event Mean Concentrations for Site D for all Sampled Events

43. Results Arithmetic Mean and Median for First Flush and Event Mean Concentrations for Site E for all Sampled Events

44. Load Calculation L= C V L = Event Pollutant Load (Kg/event) C = Event Mean Concentration (Kg/m3 ) V = Volume of Runoff (m3 /event)

45. Pollutant Loads for Site A

46. Pollutant Loads for Site C

47. Pollutant Loads for Site D

48. Pollutant Loads for Site E

49. Cr Concentration versus TSS Concentrationfor the West Pipe Outlet

50. Cr Concentration versus TSS Concentrationfor the East Pipe Outlet

51. Cr Concentration versus TSS Concentrationfor the Basin Outlet Pipe

52. Conclusions of Field Study Roadside vegetation showed strong potential to reduce runoff via infiltration. Metals (Cu, Cd, and Zn), COD, TSS, and TDS are the primary contaminants found in the highway runoff. SVOCs and VOCs were below the detection limits. A weak correlation between concentrations, TSS, antecedent dry period (ADP), total rainfall, and volume of runoff. The existing BMP seems to be somewhat effective in reducing the heavy metals, chloride, COD, and TSS loads. Effectiveness is limited to low intensity rainfall events.

53. Vegetated Swale DesignCriteria WQV flow depth < 4 inches WQV velocity