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Evolution of Trash Management for Caltrans Freeways By:

Evolution of Trash Management for Caltrans Freeways By:. Timothy Sobelman, Caltrans David Alderete, CSUS Office of Water Programs James Sullivan, Metcalf & Eddy, Inc. Foster McMasters, Metcalf & Eddy, Inc. . Outline. Introduction Pilot Program Transitioning from Pilot Studies

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Evolution of Trash Management for Caltrans Freeways By:

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  1. Evolution of Trash Management for Caltrans FreewaysBy: • Timothy Sobelman, Caltrans • David Alderete, CSUS Office of Water Programs • James Sullivan, Metcalf & Eddy, Inc. • Foster McMasters, Metcalf & Eddy, Inc.

  2. Outline • Introduction • Pilot Program • Transitioning from Pilot Studies • Hydraulic Criteria • GSRD Design Development • Challenges in Developing a Range of Sizes • Conclusion

  3. Introduction

  4. Trash after a storm event in Long Beach Harbor

  5. Pilot Program

  6. Caltrans GSRD Pilot Program • Initiated in 2000 • Full-scale, field pilot studies • Full-scale, lab hydraulic studies

  7. Trash TMDLs • Numeric Target = 0 • Timeframe = 12 or 13 years • Compliance = “Full Capture System” 2,600 Outfalls

  8. Gross Solids + Litter Vegetative Material • Plastic • Glass • Metal • 5 mm (0.25 in) • Leaves • Organic Material

  9. Gross Solids

  10. Develop Concepts • “Full Capture System” • Small footprint • Non-proprietary • Safety • Maintenance Friendly

  11. “Full Capture System” • Traps all particles retained by a 5-mm (0.25-in) mesh screen • Design treatment capacity: 1-year, 1-hour storm (around 0.6 in/hr)

  12. Requirement – Safety • Pass design Q (25-year peak flow) • Drain within 72 hours (vectors)

  13. Goal – Maintenance Friendly • Hold 1-year’s worth of gross solids 0.7 m3 / ha / yr (10 ft3 / ac / yr) • Ease of cleaning

  14. Cleaning Techniques Examined • Hand Cleaning • Bags • Boom Truck • Vactor Truck • Bucket

  15. Linear Radial – Config. 1 Well-screen Linear Radial Recommend Approval

  16. Linear Radial – Config. 2 Mesh-cage Linear Radial Excessive Maintenance

  17. Inclined Screen – Config. 1 Wedge-wire Inclined Screen Recommend Approval

  18. Inclined Screen – Config. 2 Vertical Bar Inclined Screen Excessive Maintenance

  19. Baffle Box Excessive Maintenance

  20. Inclined Screen – Config. 3 Loader Inclined Screen Still Evaluating

  21. Inclined Screen – Config. 4 Direct Flow Inclined Screen Recommend Approval

  22. V-Screen – Config. 1 Forward Sloping Screen Excessive Maintenance

  23. V-Screen – Config. 2 Reverse Sloping Screen Excessive Maintenance

  24. Transitioning from Pilot Studies

  25. Transitioning from Pilot Study to Full Scale Implementation - Linear Radial Characteristics • Low hydraulic head required • Debris storage area limited by 2 ft (600 mm) Screen Diameter • Standardized on 5 ft (1500 mm) Screen Length • Shape is “long & skinny” • Limits placement options • Hatches in screen to facilitate debris removal

  26. Linear Radial Isometric View

  27. Transitioning from Pilot Study to Full Scale Implementation – Inclined Screen Characteristics • Requires 5.5 ft (1.67 m) of hydraulic head • Good self cleaning screen characteristics • Inlet energy dissipation is integral to design • Grating provided to limit wind blown debris • Large debris storage area • Square plan shape

  28. Inclined Screen Type 1 Isometric View

  29. Inclined Screen Type 2 Isometric View

  30. Hydraulic Criteria

  31. Type Designation Screen Length (meters) Design Flow Rate (m3/sec) Debris Area (hectares) LR-1 1.5 0.10 0.32 LR-2 3.0 0.20 0.64 LR-3 4.6 0.31 0.91 LR-4 6.1 0.41 1.28 LR-5 7.6 0.52 1.60 LR-6 9.1 0.62 1.92 Hydraulic Criteria - Linear Radial

  32. Type Designation Screen Length (meters) Design Flow Rate (m3/sec) Debris Area (hectares) 1-A 4 0.25 1.45 1-B 6 0.37 3.26 1-C 8 0.49 5.81 Hydraulic Criteria - Inclined Screen Type 1

  33. Type Designation Screen Length (meters) Design Flow Rate (m3/sec) Debris Area (hectares) 2-A 1.0 0.06 0.41 2-B 1.5 0.09 0.61 2-C 2.0 0.12 0.81 2-D 2.5 0.15 1.01 Hydraulic Criteria - Inclined Screen Type 2

  34. GSRD Design Development

  35. GSRD Design Development Procedure During Phase I Design • Two projects in LA County are the first Phase • 52 drainage sites initially selected along Interstates 405, 710 and State Route 60. • Basis for range of standard GSRD sizes • Site layout plans prepared • Tributary areas defined • basis for hydraulic and gross solids sizing • Existing pipe size, capacity and velocity calculated • Site constraints verified

  36. Challenges in Developing a Range of Sizes

  37. Challenges in Developing Range of Sizes - Design Condition Definition • Typical design versus site specific • High velocities needs energy dissipation • Wide variety of side slope conditions

  38. Conclusions • Los Angeles Water Quality Goals Require Capture of “Gross Solids” • Typical GSRD Plans will Help Caltrans Engineers Prepare Cost-Effective Projects • Feedback from Phase 1 Construction will be used to Refine and Improve the Standard GSRD Details • Pilot sites do not necessarily represent typical conditions for full scale implementation

  39. Questions?

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