Stormwater Maintenance Awareness Training, Part III: Above Ground Facilities, October 6, 2015

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)
Fall 2015

2. Stormwater Maintenance Awareness Training
MSMD/DPWES
Course Schedule
AM 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/questions
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NOTE: All pictures, unless noted, are the property of Fairfax County.

3. Stormwater Maintenance Awareness Training
MSMD/DPWES
Above Ground Facilities-Infiltration Trenches (TR)
• Provides some quantity control and treats runoff through
filtration/infiltration
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4. Stormwater Maintenance Awareness Training
MSMD/DPWES
Above Ground Facilities-Infiltration Trenches (TR)
Properly Functioning Examples: (Typical single-family residential lot facilities)
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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”.

5. Stormwater Maintenance Awareness Training
MSMD/DPWES
Above Ground Facilities-Infiltration Trenches (TR)
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Picture: VDEQ Stormwater Design Specification No. 8, Infiltration Practices, Version 1.9, 3/1/11

6. Stormwater Maintenance Awareness Training
MSMD/DPWES
Above Ground Facilities-Infiltration Trenches (TR)
Sediment Accumulation and Curb Cuts
6
TOP 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

7. Stormwater Maintenance Awareness Training
Above Ground Facilities-Infiltration Trenches (TR)
Deficiencies Requiring Action:
Plantings and 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

8. Stormwater Maintenance Awareness Training
MSMD/DPWES
Above Ground Facilities-Infiltration Trenches (TR)
Turf Covered TRs
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Some 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

9. Stormwater Maintenance Awareness Training
MSMD/DPWES
Above Ground Facilities-Infiltration Trenches (TR)
Cleanouts/Observation Wells
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Other common issues:
• Caps stuck/not removable
• Clogged cleanouts
• Presence of standing water in the cleanout
Broken/damaged well cap Missing cap

10. Stormwater Maintenance Awareness Training
MSMD/DPWES
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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11. Stormwater Maintenance Awareness Training
MSMD/DPWES
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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12. Stormwater Maintenance Awareness Training
MSMD/DPWES
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 in commercial,
institutional, & residential sites
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Properly Functioning Examples:

13. Stormwater Maintenance Awareness Training
MSMD/DPWES
Above Ground Facilities-Permeable Pavement (PP)
Key components
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14. Stormwater Maintenance Awareness Training
MSMD/DPWES
Above Ground Facilities-Permeable Pavement (PP)
Key components
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Picture: VDEQ Stormwater Design Specification No. 7, Permeable Pavement, Version 1.8, 3/1/11, Figure 7.1 (as noted)

15. Stormwater Maintenance Awareness Training
MSMD/DPWES
Above Ground Facilities-Permeable Pavement (PP)
Deficiencies Requiring Action
Pervious Layer
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Sediment/Silt
Weeds/overgrown
vegetation
Deterioration &/or cracks
in pervious layer

16. Stormwater Maintenance Awareness Training
MSMD/DPWES
Above Ground Facilities-Permeable Pavement (PP)
Outfall Structure/Underdrain
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Damaged underdrains
Clogging and/or a potential
blockage in the outfall
structure/underdrain
Blockage in the underdrain

17. Stormwater Maintenance Awareness Training
MSMD/DPWES
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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18. Stormwater Maintenance Awareness Training
MSMD/DPWES
Above Ground Facilities-Permeable Pavement (PP)
• Common Remedies
– 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
• Remove any non-spec vegetation, especially if it impacts the health
and function of the facility, as designed.
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19. Stormwater Maintenance Awareness Training
MSMD/DPWES
Above Ground Facilities-Rooftop Detention (RT)
• Designed to slow the flow from the
roof through short-term ponding
on the roof surface
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Properly Functioning Examples of
Rooftop Detention Devices:
Ring with
1” holes
Slotted square
detention
device
Adjustable
detention
device
Custom
devices

20. Stormwater Maintenance Awareness Training
MSMD/DPWES
Above Ground Facilities-Rooftop Detention (RT)
Properly Functioning Examples:
Scuppers convey emergency overflow off rooftop
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21. Stormwater Maintenance Awareness Training
MSMD/DPWES
Above Ground Facilities-Rooftop Detention (RT)
Deficiencies Requiring Action
Scuppers and Adjustable Detention Devices
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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

22. Stormwater Maintenance Awareness Training
MSMD/DPWES
Above Ground Facilities-Rooftop Detention (RT)
Parapet Walls, Vegetation, and Detention Devices
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Parapet wall missing
Debris Sediment Sediment
Tree growing on roof surface

23. Stormwater Maintenance Awareness Training
MSMD/DPWES
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
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24. Stormwater Maintenance Awareness Training
MSMD/DPWES
Above Ground Facilities-Rooftop Detention (RT)
• For more information call 703-877-2800, TTY 711
• Maintenance and Stormwater Management
• Department of Public Works and Environmental Services
• Fairfax County, Va.
• www.fairfaxcounty.gov
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