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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
MSMD/DPWES
Course ScheduleAM session (includes two 15 minute 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 (the rest of the story….)
12:00-1:00 PM Lunch
PM session (includes two 15 minute 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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Stormwater Maintenance Awareness Training
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Above Ground Facilities-Infiltration Trenches (TR)
Provides some quantity control & treats runoff through filtration/infiltration
May be designed to treat surface runoff or piped drainage (downspouts)
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Stormwater Maintenance Awareness Training
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Above Ground Facilities-Infiltration Trenches (TR)
Properly Functioning Examples: (Typical single-family residential lot facilities)
LEFT: Picture shows a gravel infiltration trench with a cleanout and observation well, during a soil probe test. A soil probe is pushed into the underlying gravel layer to determine the topsoil depth and confirm facility is “per design”.
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Stormwater Maintenance Awareness Training
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Above Ground Facilities-Infiltration Trenches (TR)
Picture: VDEQ Stormwater Design Specification No. 8, Infiltration Practices, Version 1.9, 3/1/11
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Above Ground Facilities-Infiltration Trenches (TR)
Sediment Accumulation & Curb CutsTOP LEFT: Some debris and sediment on surface at curb cut
BOTTOM LEFT: Curb cut blocked (remove wheel stop)
TOP RIGHT: Surface debris & sediment accumulation
BOTTOM RIGHT: Sediment accumulation in gravel bed
Stormwater Maintenance Awareness Training
Above Ground Facilities-Infiltration Trenches (TR)
Deficiencies Requiring Action:Plantings & Overgrown Vegetation
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Downed tree limb with deep-rooted/overgrown vegetation
Overgrown vegetation within the limits of a gravel bed trench may indicate sediment accumulation, as plants do not tend to grow in clean gravel.
Unauthorized plantings
MSMD/DPWES
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Stormwater Maintenance Awareness Training
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Above Ground Facilities-Infiltration Trenches (TR)
Turf Covered TRsSome trenches may have turf and topsoil, covering the gravel bed; however, turf is not automatically acceptable. ALWAYS refer to the approved site plan! • A soil probe test checks the gravel layer
(refer to slide 4).• Water usually reaches the gravel bed
through underground PVC pipes connected to the roof drain downspouts.
Common issues include:• Missing underground gravel beds• Disconnected roof downspouts draining
overland instead of via an underground pipe
• Bare spots/exposed soil in turf covering• Missing berms or observation wells
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Stormwater Maintenance Awareness Training
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Above Ground Facilities-Infiltration Trenches (TR)
Cleanouts/Observation Wells
Other common issues: • Caps stuck/not removable• Clogged cleanouts• Presence of standing water in the cleanout
Broken/damaged well cap Missing cap
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Above Ground Facilities-Infiltration Trenches (TR)• Common Remedies
– Remove all flow blockages as well as any additional trash, debris, and accumulated sediment• Special attention should be given, as required to gravel beds
(surface and within gravel pores) and may require removal/replacement of clogged sections of gravel
• Fully remove any plants growing in the accumulated sediments– Full removal includes eliminating roots and supporting
soil/sediment from the gravel bed, as spraying weed killer is not a sufficient treatment solution
– 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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Stormwater Maintenance Awareness Training
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Above Ground Facilities-Infiltration Trenches (TR)• Common Remedies
– 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
• 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
– Cut back overgrown vegetation around facility structures to facilitate access and proper function
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Stormwater Maintenance Awareness Training
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Above Ground Facilities-Permeable Pavement (PP)
• Alternative paving surface which treats runoff through filtration (voids in paved surface), temporary storage (underlying stone reservoir), and infiltration– Includes permeable pavement,
pervious concrete, porous asphalt, and permeable pavers
– PP promotes a high degree of runoff volume reduction & nutrient removal
– Primarily used on commercial, institutional, & residential sites
Properly Functioning Examples:
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Stormwater Maintenance Awareness Training
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Above Ground Facilities-Permeable Pavement (PP)
Key components
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Stormwater Maintenance Awareness Training
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Above Ground Facilities-Permeable Pavement (PP)
Key components
Picture: VDEQ Stormwater Design Specification No. 7, Permeable Pavement, Version 1.8, 3/1/11, Figure 7.1 (as noted)
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Stormwater Maintenance Awareness Training
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Above Ground Facilities-Permeable Pavement (PP)
Deficiencies Requiring ActionPervious Layer
Sediment/SiltWeeds/overgrown
vegetationDeterioration &/or cracks
in pervious layer
Asphalt Sealed?
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Stormwater Maintenance Awareness Training
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Above Ground Facilities-Permeable Pavement (PP)
Outfall Structure/Underdrain
Damaged underdrains
Clogging and/or a potential blockage in the outfall structure/underdrain
Blockage in the underdrain
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Stormwater Maintenance Awareness Training
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Above Ground Facilities-Permeable Pavement (PP)
• Common Remedies– Remove all flow blockages as well as any additional trash, debris, and
accumulated sediment• Perform a thorough restorative vacuum sweep of paved surface• Investigate the causes of any blockages to prevent re-occurrence, if
at all possible.– 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
• Specific to this facility type: any damaged, cracked, or failing pavers or paved sections
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Stormwater Maintenance Awareness Training
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Above Ground Facilities-Permeable Pavement (PP)
• Common Remedies– Rebuild/stabilize any areas of erosion:
• Adjoining land erosion can silt in permeable pavement– Remove vegetation in permeable pavement to facilitate proper function
• Remove any non-spec vegetation, especially if it impacts the health and function of the facility, as designed.
– Sealed permeable pavement requires a complete replacement
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Stormwater Maintenance Awareness Training
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Above Ground Facilities-Rooftop Detention (RT)• Designed to slow the flow from the
roof through short-term ponding on the roof surface
Properly Functioning Examples of Rooftop Detention Devices:
Ring with 1” holes
Slotted square detention
device
Adjustable detention
device
Custom devices
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Above Ground Facilities-Rooftop Detention (RT)Properly Functioning Examples: Scuppers convey emergency overflow off rooftop
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Above Ground Facilities-Rooftop Detention (RT)Deficiencies Requiring ActionScuppers and Adjustable Detention Devices
Scupper not providing proper water detention because it is
level with roof
Adjustable detention device opened too
wide
Detention device and debris cage
missing
Debris cage is damaged and
detention device missing
Incorrect number of drains and/or scuppers (usually too many)
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Stormwater Maintenance Awareness Training
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Above Ground Facilities-Rooftop Detention (RT)
Parapet Walls, Vegetation, and Detention Devices
Parapet wall missing
Debris Sediment Sediment
Tree growing on roof surface
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Stormwater Maintenance Awareness Training
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Above Ground Facilities-Rooftop Detention (RT)• Common Remedies
– Remove all flow blockages as well as any additional trash, debris, and accumulated sediment
– 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
– Remove ANY vegetation around facility structures and on rooftop– Provide required detention flow rate
• Replace any missing or damaged detention devices and debris cages• Re-adjust detention devices, as needed• Raise scuppers that are too low or provide detention at the scupper• Repair or install any missing parapet walls• Recalculate the flow based on the actual number of drains to attain the
prescribed detention
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Stormwater Maintenance Awareness Training
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Above Ground Facilities-Rooftop Detention (RT)
LUNCH!Please be back & ready to start at 1:00 PM
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