NDOR Research Conference: Dr. Zhang
Preview:
DESCRIPTION
Nebraska Department of Roads Conference 2012Presented by Dr. Tian Zhang
Citation preview
- 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