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Stormwater Management Awareness Training 4

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The Stormwater Maintenance Awareness Training course discusses below ground facilities.

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Stormwater Management Awareness Training 4

  1. 1. A Fairfax County, VA, publication Department of Public Works and Environmental Services Working for You! Stormwater Maintenance Awareness Training For privately maintained stormwater management facilities Maintenance and Stormwater Management Division (MSMD) Winter 2018
  2. 2. Stormwater Maintenance Awareness Training MSMD/DPWES Course Schedule AM session (includes two short breaks) – History of SWM and regulations – County inspection basics – The inspection report and MAR – Common SWM/BMP types • Common maintenance items-General – Common SWM/BMP types, deficiencies, and remedies • Above Ground Facilities 12:00-1:00 PM Lunch PM session (includes two short breaks) – Common SWM/BMP types, deficiencies, and remedies • Below Ground Facilities • Vegetative Practices – Closing remarks/questions 2 NOTE: All pictures, unless noted, are the property of Fairfax County.
  3. 3. Stormwater Maintenance Awareness Training MSMD/DPWES Below Ground Facilities-General Safety 3 The County’s private inspection program does NOT allow for Confined Space Entry! Please ensure you are properly certified, have the proper entry permits, and are appropriately equipped before entering any applicable confined space!
  4. 4. Stormwater Maintenance Awareness Training MSMD/DPWES Below Ground Facilities-General Safety 4 The County’s private inspection program does NOT allow for Confined Space Entry! Please ensure you are properly certified, have the proper entry permits, and are appropriately equipped before entering any applicable confined space! In the event that CSE is necessary for proper facility maintenance • Any confined space entry must be conducted by personnel with proper training and equipment
  5. 5. Stormwater Maintenance Awareness Training MSMD/DPWES Below Ground Facilities-Underground Detention (UG) • An underground basin which temporarily stores stormwater runoff • Control structure • Inflow • Detention structure • Outfall 5 Picture: Georgia Stormwater Management Manual 3.4-15, figure 3.4.3-1 “Example Underground Detention Tank System” UNDERGROUND DETENTION COMPONENTS
  6. 6. Stormwater Maintenance Awareness Training MSMD/DPWES Below Ground Facilities-Underground Detention (UG) • Detention Pipe/Vault Types: – Corrugated Metal Pipe (CMP) – Concrete pipe – Box culvert – HDPE (High-density Polyethylene) – Large concrete vault 6 NOTE: Some of these photos may show deficiencies as well as pipe/vault types.
  7. 7. Stormwater Maintenance Awareness Training MSMD/DPWES Below Ground Facilities-Underground Detention (UG) • Control Weir & Orifice Types: – Concrete – CMP Half-Round – Multiple orifices 7 NOTE: Some of these photos may show deficiencies as well as control weir/orifice types.
  8. 8. Stormwater Maintenance Awareness Training MSMD/DPWES Below Ground Facilities-Underground Detention (UG) • “TRUGS” Some UGs include underground trenches, composed of a perforated pipe within an aggregate bed or a plastic modular structure, both meant to incorporate groundwater infiltration capabilities into the facility. 8 Perforated pipe with aggregate bed design examples: Modular, stackable design Perforated CMP Concrete with drilled holes NOTE: Some of these photos may show deficiencies as well as TRUG design types.
  9. 9. Stormwater Maintenance Awareness Training MSMD/DPWES Below Ground Facilities-Underground Detention (UG) Routine Deficiencies Observed Pipes (Sediment/Debris Accumulation) 9 Debris and sediment accumulation inside pipes
  10. 10. Stormwater Maintenance Awareness Training MSMD/DPWES Below Ground Facilities-Underground Detention (UG) Pipes (Damage and Deterioration) 10 Damage and/or deterioration inside pipes
  11. 11. Stormwater Maintenance Awareness Training MSMD/DPWES Below Ground Facilities-Underground Detention (UG) Pipes (Damage and Deterioration, Continued) 11 Spalling and exposed rebar Spalling and deterioration of control structure’s outflow pipe
  12. 12. Stormwater Maintenance Awareness Training MSMD/DPWES Below Ground Facilities-Underground Detention (UG) Pipes (Damage and Deterioration, Continued) 12 Patching brick work around pipes…
  13. 13. Stormwater Maintenance Awareness Training MSMD/DPWES Below Ground Facilities-Underground Detention (UG) Control Structure (Sediment/Debris Accumulation and Concrete Damage) 13 Trash/debris/sediment in control structure Standing water after several dry weather days indicates a flow blockage Deterioration and spalling around control structure
  14. 14. Stormwater Maintenance Awareness Training MSMD/DPWES Below Ground Facilities-Underground Detention (UG) Orifice Blockage and Missing Components 14 Downstream view of orifice blockage Upstream views of orifice blockages
  15. 15. Stormwater Maintenance Awareness Training MSMD/DPWES Below Ground Facilities-Underground Detention (UG) Trash Rack and Orifice Plate (Blockages, damage, missing components, etc.) 15 Sediment build-up, looking upstream through the orificePonded water suggests a possible orifice blockage Debris blocks trash rack
  16. 16. Stormwater Maintenance Awareness Training MSMD/DPWES Below Ground Facilities-Underground Detention (UG) • Common Remedies – Remove all flow blockages as well as any additional trash, debris, and accumulated sediment • Special attention should be given, as required, to a thorough vacuum and Hydrojet of the interior of structure – Repair/replace any damaged/missing components • Components vary by facility type and design, and they can range from parts to structural to environmental materials (see prior noted examples) – Check plans for specific facility requirements – Rebuild/stabilize any areas with erosion, cave-ins, and bare spots: • Cave-ins require additional investigation to determine cause and prevent re-occurrence 16
  17. 17. Stormwater Maintenance Awareness Training MSMD/DPWES Below Ground Facilities-Underground Detention (UG) • Common Remedies – Repair/replace any damaged/missing components (continued) • For damaged/misaligned pipes: – Reinforce/repair, if possible (Internal bands and gaskets) – Slip-line pipes when possible – Excavate and replace/reseal, if first two options are not possible – Obtain appropriate Confined Space Certification for applicable systems 17
  18. 18. Stormwater Maintenance Awareness Training MSMD/DPWES Below Ground Facilities-Sand Filters (SF) • Provide water quality control by filtering stormwater through a gravel and sand bed 18 • Different sand filter types and components: – D.C. Sand Filter (In-Line) – Delaware Sand Filter (Side-by-Side) – Austin Sand Filter (Above-Ground) Filter chambers in good condition D.C. SAND FILTER
  19. 19. Stormwater Maintenance Awareness Training MSMD/DPWES Below Ground Facilities-Sand Filters (SF) 19 Filter chambers in good to moderate condition Sediment Chamber Clearwell Filter Chamber Delaware Sand Filter SAND FILTER COMPONENTS
  20. 20. Stormwater Maintenance Awareness Training MSMD/DPWES Below Ground Facilities-Sand Filters (SF) • Gravel riprap • Sand • Cleanouts 20 Austin Sand Filter SAND FILTER COMPONENTS • Perforated underdrain • Geotextile fabric • Outfall pipe
  21. 21. Stormwater Maintenance Awareness Training MSMD/DPWES Below Ground Facilities-Sand Filters (SF) Routine Deficiencies Observed Sedimentation and Filter Chambers (Trash/debris accumulation) 21 Debris in the Sedimentation Chamber Trash and sediment accumulation in the Filter Chamber - If a filter chamber is still holding water after three days of dry weather, it is likely clogged or blocked.
  22. 22. Stormwater Maintenance Awareness Training MSMD/DPWES Below Ground Facilities-Sand Filters (SF) Dewatering Valves (open or missing) 22 Dewatering valves must remain CLOSED, except during maintenance activities or the facility will be non-functional. Valve not fully closed One of the valves has fallen off and is lying on the chamber floor
  23. 23. Stormwater Maintenance Awareness Training MSMD/DPWES Below Ground Facilities-Sand Filters (SF) Dewatering Valves/Confined Space What are some of the safety concerns and improper practices shown in this picture? 23
  24. 24. Stormwater Maintenance Awareness Training MSMD/DPWES Below Ground Facilities-Sand Filters (SF) Filter Media (Uneven) 24 These photos are all from the same sand filter facility.
  25. 25. Stormwater Maintenance Awareness Training MSMD/DPWES Below Ground Facilities-Sand Filters (SF) • Common Remedies – Remove all flow blockages as well as any additional trash, debris, and accumulated sediment • Special attention should be given, as required, to a thorough vacuum and Hydrojet of the interior of structure • Do not Hydrojet the filter chamber – Removal/replacement of top layer of filter bed may be required – Repair/replace any damaged/missing components • Components vary by facility type and design, and they can range from parts to structural to environmental materials (see prior noted examples) – Check approved site plans for specific facility requirements 25
  26. 26. Stormwater Maintenance Awareness Training MSMD/DPWES Below Ground Facilities-Sand Filters (SF) • Common Remedies – Repair/replace any damaged/missing components (continued) • For damaged/misaligned pipes: – Reinforce/repair, if possible (Internal bands and gaskets) – Slip-line pipes when possible, as this may be most cost effective – Excavate and replace/reseal, if first two options are not possible – Rebuild/stabilize any areas with erosion, cave-ins, and bare spots: • Cave-ins require additional investigation to determine cause and prevent re-occurrence – Obtain appropriate Confined Space Certification for applicable systems – Maintenance for Austin sand filters may be similar to that for a dry pond 26
  27. 27. Stormwater Maintenance Awareness Training MSMD/DPWES Below Ground Facilities-Manufactured BMPs (MB) • A pre-fabricated stormwater treatment structure utilizing one or more of the following to remove pollutants from stormwater runoff: – Settling – Filtration – Absorptive/adsorptive materials – Vortex separation – Vegetative components • There are many kinds of MBs, which fall into two types: – Non-proprietary (public-domain) – Proprietary (patented or factory-made*) • Follow manufacturer’s maintenance recommendations, which may require the contractor to be certified to perform the maintenance 27 * Note proprietary MBs are attributed (to the extent possible) to the patent holder as identified at the time of training material preparation. The following examples are commonly available/utilized technology. The inclusion of these products as examples for training purposes does not constitute any real or implied endorsement of these products by Fairfax County.
  28. 28. Stormwater Maintenance Awareness Training MSMD/DPWES Below Ground Facilities-Manufactured BMPs (MB) Example of a non-proprietary MB: Oil-Grit Separator 28 Picture: US Department of Transportation, Stormwater Best Management Practices in an Ultra-Urban Setting: Selection and Monitoring, Fact Sheet: Oil/Grit Separator Units”, https://www.environment.fhwa.dot.gov/ecosystems/ultraurb/3fs12.asp
  29. 29. Stormwater Maintenance Awareness Training MSMD/DPWES Below Ground Facilities-Manufactured BMPs (MB) Example of a proprietary MB: StormFilter (Plan Detail for MB0173) 29 InletBay Cartridge Bay OutletBay www.conteches.com
  30. 30. Stormwater Maintenance Awareness Training MSMD/DPWES Below Ground Facilities-Manufactured BMPs (MB) 30 ABOVE: StormFilter cartridge RIGHT: 33+ cartridges during installation www.conteches.com STORMFILTER COMPONENTS
  31. 31. Stormwater Maintenance Awareness Training MSMD/DPWES Below Ground Facilities-Manufactured BMPs (MB) 31 Energy dissipater or level spreader is located at the upstream end of the cartridge bay www.conteches.com STORMFILTER COMPONENTS
  32. 32. Stormwater Maintenance Awareness Training MSMD/DPWES Below Ground Facilities-Manufactured BMPs (MB) 32 Flow spreader www.conteches.com Underdrain pipes STORMFILTER COMPONENTS
  33. 33. Stormwater Maintenance Awareness Training MSMD/DPWES Below Ground Facilities-Manufactured BMPs (MB) 33 StormGate directs low flows toward the StormFilter while allowing higher flows to bypass StormGate www.conteches.com STORMFILTER COMPONENTS
  34. 34. Stormwater Maintenance Awareness Training MSMD/DPWES Below Ground Facilities-Manufactured BMPs (MB) Example of a proprietary MB: Vortech Stormwater Treatment System 34 Hydrodynamic Separation www.conteches.com
  35. 35. Stormwater Maintenance Awareness Training MSMD/DPWES Below Ground Facilities-Manufactured BMPs (MB) Example of a proprietary MB: Stormceptor 35
  36. 36. Stormwater Maintenance Awareness Training MSMD/DPWES Below Ground Facilities-Manufactured BMPs (MB) Example of a proprietary MB: Downstream Defender 36 Hydrodynamic Separation http://www.hydro-int.com/us/products/ downstream-defender
  37. 37. Stormwater Maintenance Awareness Training MSMD/DPWES Below Ground Facilities-Manufactured BMPs (MB) Example of a proprietary MB: StormTreat System 37 www.stormtreat.com Bio-Media Filtration
  38. 38. Stormwater Maintenance Awareness Training MSMD/DPWES Below Ground Facilities-Manufactured BMPs (MB) Routine Deficiencies Observed Accumulated Trash/Debris/Grit/Sediment/Floatables 38 Collected grit, sediment, and floatable debris in the Oil/Grit Separator Regular maintenance is required to remove collected materials like these Trash, sediment, and debris in the StormFilter
  39. 39. Stormwater Maintenance Awareness Training MSMD/DPWES Below Ground Facilities-Manufactured BMPs (MB) Spalling/Deterioration/Damage to Components 39 Spalling and exposed rebar around pipe end, inside chamber looking downstream toward outfall
  40. 40. Stormwater Maintenance Awareness Training MSMD/DPWES Below Ground Facilities-Manufactured BMPs (MB) Common Remedies • Proprietary MBs – Follow Manufacturers Guidance/Recommendations • Non-Proprietary MBs – Remove all flow blockages as well as any additional trash, debris, and accumulated sediment • Special attention should be given, as required, to a thorough vacuum and hydrojet of the interior of structure – Repair/replace any damaged/missing components • Components vary by facility type and design, and they can range from parts to structural to environmental materials (see prior noted examples) – Check plans for specific facility requirements 40
  41. 41. Stormwater Maintenance Awareness Training MSMD/DPWES Below Ground Facilities-Manufactured BMPs (MB) Common Remedies • Non-Proprietary MBs (continued) – Repair/replace any damaged/missing components (continued) • For damaged/misaligned pipes: – Reinforce/repair, if possible (internal bands and gaskets) – Slip-line pipes when possible, as this may be most cost effective – Excavate and replace/reseal, if first two options are not possible – Rebuild/stabilize any areas with erosion, cave-ins, and bare spots: • Cave-ins require additional investigation to determine cause and prevent re-occurrence – Cut back overgrown vegetation around facility structures to facilitate access and proper function – Obtain appropriate Confined Space Certification for applicable systems 41
  42. 42. Additional Information For additional information, please contact MSMD/DPWES 42 Todd Nelson 703-877-2800, TTY 711 www.fairfaxcounty.gov/publicworks

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