Contractor Awareness Training Below Ground Facilities 2016
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This document provides an overview of a stormwater maintenance awareness training held by the Department of Public Works and Environmental Services in Fairfax County, VA. The training covered the history of stormwater regulations, types of stormwater management facilities like underground detention, sand filters, and manufactured BMPs. It discussed common maintenance issues for these facilities like debris and sediment accumulation, damage to components, and remedial actions required. The document included pictures of different facility components and deficiencies to illustrate key points.
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Contractor Awareness Training Below Ground Facilities 2016
- 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) Spring 2016
- 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 issues-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. 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. Stormwater Maintenance Awareness Training MSMD/DPWES Below Ground Facilities-Underground Detention (UG) • An underground basin which temporarily stores stormwater runoff • Key components include: – Control structure – Inflow – Detention structure – Outfall 4 Picture: Georgia Stormwater Management Manual 3.4-15, figure 3.4.3-1 “Example Underground Detention Tank System”
- 5. 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 5 NOTE: Some of these photos may show deficiencies as well as pipe/vault types.
- 6. Stormwater Maintenance Awareness Training MSMD/DPWES Below Ground Facilities-Underground Detention (UG) • Control Weir & Orifice Types: – Concrete – CMP Half-Round – Multiple orifices 6 NOTE: Some of these photos may show deficiencies as well as control weir/orifice types.
- 7. 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. 7 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.
- 8. Stormwater Maintenance Awareness Training MSMD/DPWES Below Ground Facilities-Underground Detention (UG) Deficiencies Requiring Action Pipes (Sediment/Debris Accumulation) 8 Debris and sediment accumulation inside pipes
- 9. Stormwater Maintenance Awareness Training MSMD/DPWES Below Ground Facilities-Underground Detention (UG) Pipes (Damage and Deterioration) 9 Damage and/or deterioration inside pipes
- 10. Stormwater Maintenance Awareness Training MSMD/DPWES Below Ground Facilities-Underground Detention (UG) Pipes (Damage and Deterioration, Continued) 10 Spalling and exposed rebar Spalling and deterioration of control structure’s outflow pipe
- 11. Stormwater Maintenance Awareness Training MSMD/DPWES Below Ground Facilities-Underground Detention (UG) Pipes (Damage and Deterioration, Continued) 11 Patching brick work around pipes…
- 12. Stormwater Maintenance Awareness Training MSMD/DPWES Below Ground Facilities-Underground Detention (UG) Control Structure (Sediment/Debris Accumulation and Concrete Damage) 12 Trash/debris/sediment in control structure Standing water after several dry weather days indicates a flow blockage Deterioration and spalling around control structure
- 13. Stormwater Maintenance Awareness Training MSMD/DPWES Below Ground Facilities-Underground Detention (UG) Orifice Blockage and Missing Components 13 Downstream view of orifice blockage Upstream views of orifice blockages
- 14. Stormwater Maintenance Awareness Training MSMD/DPWES Below Ground Facilities-Underground Detention (UG) Trash Rack and Orifice Plate (Blockages, damage, missing components, etc.) 14 Sediment build-up, looking upstream through the orificePonded water suggests a possible orifice blockage Debris blocks trash rack
- 15. Stormwater Maintenance Awareness Training MSMD/DPWES Above 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 15
- 16. Stormwater Maintenance Awareness Training MSMD/DPWES Above 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 16
- 17. 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 17 • Components of different sand filter types: – 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
- 18. Stormwater Maintenance Awareness Training MSMD/DPWES Below Ground Facilities-Sand Filters (SF) • Components of Different Sand Filter Types: 18 Filter chambers in good to moderate condition Sediment Chamber Clearwell Filter Chamber Delaware Sand Filter
- 19. Stormwater Maintenance Awareness Training MSMD/DPWES Below Ground Facilities-Sand Filters (SF) • Components of Different Sand Filter Types: 19 Austin Sand Filter
- 20. Stormwater Maintenance Awareness Training MSMD/DPWES Below Ground Facilities-Sand Filters (SF) Deficiencies/Conditions Requiring Action Sedimentation and Filter Chambers (Trash/debris accumulation) 20 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.
- 21. Stormwater Maintenance Awareness Training MSMD/DPWES Below Ground Facilities-Sand Filters (SF) Dewatering Valves (open or missing) 21 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
- 22. 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? 22
- 23. Stormwater Maintenance Awareness Training MSMD/DPWES Below Ground Facilities-Sand Filters (SF) Filter Media (Uneven) 23 These photos are all from the same sand filter facility.
- 24. Stormwater Maintenance Awareness Training MSMD/DPWES Above 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 24
- 25. Stormwater Maintenance Awareness Training MSMD/DPWES Above 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 25
- 26. 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 26 * 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.
- 27. Stormwater Maintenance Awareness Training MSMD/DPWES Below Ground Facilities-Manufactured BMPs (MB) Example of a non-proprietary Oil-Grit Separator: 27 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
- 28. Stormwater Maintenance Awareness Training MSMD/DPWES Below Ground Facilities-Manufactured BMPs (MB) • StormFilter Components (Plan Detail for MB0173) 28 InletBay Cartridge Bay OutletBay www.conteches.com
- 29. Stormwater Maintenance Awareness Training MSMD/DPWES Below Ground Facilities-Manufactured BMPs (MB) • StormFilter Components 29 ABOVE: StormFilter cartridge RIGHT: 33+ cartridges during installation www.conteches.com
- 30. Stormwater Maintenance Awareness Training MSMD/DPWES Below Ground Facilities-Manufactured BMPs (MB) • StormFilter Components 30 Energy dissipater or level spreader is located at the upstream end of the cartridge bay www.conteches.com
- 31. Stormwater Maintenance Awareness Training MSMD/DPWES Below Ground Facilities-Manufactured BMPs (MB) • StormFilter Components 31 Flow spreader www.conteches.com Underdrain pipes
- 32. Stormwater Maintenance Awareness Training MSMD/DPWES Below Ground Facilities-Manufactured BMPs (MB) • StormFilter Components 32 StormGate directs low flows toward the StormFilter while allowing higher flows to bypass StormGate www.conteches.com
- 33. Stormwater Maintenance Awareness Training MSMD/DPWES Below Ground Facilities-Manufactured BMPs (MB) • Proprietary MB-Vortech Stormwater Treatment System 33 Hydrodynamic Separation www.conteches.com
- 34. Stormwater Maintenance Awareness Training MSMD/DPWES Below Ground Facilities-Manufactured BMPs (MB) • Proprietary MB-Stormceptor 34
- 35. Stormwater Maintenance Awareness Training MSMD/DPWES Below Ground Facilities-Manufactured BMPs (MB) • Proprietary MB-Downstream Defender 35 Hydrodynamic Separation http://www.hydro-int.com/us/products/ downstream-defender
- 36. Stormwater Maintenance Awareness Training MSMD/DPWES Below Ground Facilities-Manufactured BMPs (MB) • Proprietary MB- StormTreat System 36 www.stormtreat.com Bio-Media Filtration
- 37. Stormwater Maintenance Awareness Training MSMD/DPWES Below Ground Facilities-Manufactured BMPs (MB) Deficiencies/Conditions Requiring Action Accumulated Trash/Debris/Grit/Sediment/Floatables 37 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
- 38. Stormwater Maintenance Awareness Training MSMD/DPWES Below Ground Facilities-Manufactured BMPs (MB) Spalling/Deterioration/Damage to Components 38 Spalling and exposed rebar around pipe end, inside chamber looking downstream toward outfall
- 39. 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 39
- 40. 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 40
- 41. Stormwater Maintenance Awareness Training MSMD/DPWES Above Ground Facilities-Rooftop Detention (RT) We will finish up with Vegetative Practices after a short BREAK… 41