contractor awareness training below ground facilities 2016
TRANSCRIPT
A Fairfax County, VA, publication
Department of Public Works and Environmental Services
Working for You!
Stormwater Maintenance Awareness TrainingFor privately maintained stormwater management facilities
Maintenance and Stormwater Management Division (MSMD)
Spring 2016
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Stormwater Maintenance Awareness Training
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Course ScheduleAM 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/questionsNOTE: All pictures, unless noted, are the property of Fairfax County.
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Below Ground Facilities-General Safety
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!
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Below Ground Facilities-Underground Detention (UG)
• An underground basin which temporarily stores stormwater runoff
• Key components include:– Control structure– Inflow– Detention structure– Outfall
Picture: Georgia Stormwater Management Manual 3.4-15, figure 3.4.3-1 “Example Underground Detention Tank System”
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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
NOTE: Some of these photos may show deficiencies as well as pipe/vault types.
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Below Ground Facilities-Underground Detention (UG)
• Control Weir & Orifice Types:– Concrete– CMP Half-Round– Multiple orifices
NOTE: Some of these photos may show deficiencies as well as control weir/orifice types.
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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.
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.
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Below Ground Facilities-Underground Detention (UG)
Deficiencies Requiring ActionPipes (Sediment/Debris Accumulation)
Debris and sediment accumulation inside pipes
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Stormwater Maintenance Awareness Training
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Below Ground Facilities-Underground Detention (UG)
Pipes (Damage and Deterioration)
Damage and/or deterioration inside pipes
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Below Ground Facilities-Underground Detention (UG)
Pipes (Damage and Deterioration, Continued)
Spalling and exposed rebar Spalling and deterioration of control structure’s outflow pipe
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Stormwater Maintenance Awareness Training
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Below Ground Facilities-Underground Detention (UG)
Pipes (Damage and Deterioration, Continued)
Patching brick work around pipes…
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Stormwater Maintenance Awareness Training
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Below Ground Facilities-Underground Detention (UG)
Control Structure (Sediment/Debris Accumulation and Concrete Damage)
Trash/debris/sediment in control structure
Standing water after several dry weather days indicates a
flow blockage
Deterioration and spalling around control
structure
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Below Ground Facilities-Underground Detention (UG)
Orifice Blockage and Missing Components
Downstream view of orifice blockage
Upstream views of orifice blockages
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Below Ground Facilities-Underground Detention (UG)
Trash Rack and Orifice Plate (Blockages, damage, missing components, etc.)
Sediment build-up, looking upstream through the orificePonded water suggests a possible
orifice blockage
Debris blocks trash rack
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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
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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
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Below Ground Facilities-Sand Filters (SF)• Provide water quality control by
filtering stormwater through a gravel and sand bed
• 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
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Below Ground Facilities-Sand Filters (SF)
• Components of Different Sand Filter Types:
Filter chambers in good to moderate condition
Sediment Chamber
Clearwell
Filter Chamber
Delaware Sand Filter
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Below Ground Facilities-Sand Filters (SF)
• Components of Different Sand Filter Types:
Sediment Chamber
Austin Sand Filter
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Below Ground Facilities-Sand Filters (SF)Deficiencies/Conditions Requiring ActionSedimentation and Filter Chambers (Trash/debris accumulation)
Debris in the Sedimentation ChamberTrash 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.
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Below Ground Facilities-Sand Filters (SF)
Dewatering Valves (open or missing)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
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Below Ground Facilities-Sand Filters (SF)
Dewatering Valves/Confined Space
What are some of the safetyconcerns and improper practices shown in this picture?
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Below Ground Facilities-Sand Filters (SF)
Filter Media (Uneven)
These photos are all from the same sand filter facility.
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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
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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
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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
* 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.
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Below Ground Facilities-Manufactured BMPs (MB)
Example of a non-proprietary Oil-Grit Separator:
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
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Below Ground Facilities-Manufactured BMPs (MB)
• StormFilter Components (Plan Detail for MB0173)
Inlet Bay
Cartridge Bay
Outlet B
ay
www.conteches.com
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Stormwater Maintenance Awareness Training
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Below Ground Facilities-Manufactured BMPs (MB)
• StormFilter Components
ABOVE: StormFilter cartridge
RIGHT: 33+ cartridges during installation
www.conteches.com
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Below Ground Facilities-Manufactured BMPs (MB)
• StormFilter Components
Energy dissipater or level spreader is located at the upstream end of the
cartridge bay
www.conteches.com
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Below Ground Facilities-Manufactured BMPs (MB)
• StormFilter Components
Flow spreader
www.conteches.com
Underdrain pipes
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Below Ground Facilities-Manufactured BMPs (MB)
• StormFilter Components
StormGate directs low flows toward the StormFilter while allowing higher flows to bypass
StormGate
www.conteches.com
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Below Ground Facilities-Manufactured BMPs (MB)
• Proprietary MB-Vortech Stormwater Treatment SystemHydrodynamic Separation
www.conteches.com
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Stormwater Maintenance Awareness Training
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Below Ground Facilities-Manufactured BMPs (MB)
• Proprietary MB-Stormceptor
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Below Ground Facilities-Manufactured BMPs (MB)
• Proprietary MB-Downstream DefenderHydrodynamic
Separation
http://www.hydro-int.com/us/products/downstream-defender
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Below Ground Facilities-Manufactured BMPs (MB)
• Proprietary MB- StormTreat System
www.stormtreat.com
Bio-Media Filtration
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Below Ground Facilities-Manufactured BMPs (MB)
Deficiencies/Conditions Requiring ActionAccumulated Trash/Debris/Grit/Sediment/Floatables
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
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Below Ground Facilities-Manufactured BMPs (MB)
Spalling/Deterioration/Damage to Components
Spalling and exposed rebar around pipe end, inside chamber looking downstream
toward outfall
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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
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Stormwater Maintenance Awareness Training
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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
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Above Ground Facilities-Rooftop Detention (RT)
We will finish up with Vegetative Practices after a short
BREAK…