contractor awareness training vegetative practices 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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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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Vegetative Practices-Bio-Retention (BR)• Collects both piped and surface
runoff into a shallow landscaped depression incorporating pollutant removal mechanisms, filtration, and infiltration characteristics which mimic pre-development conditions– Infiltration is through a filter
bed of sand, soil and organic material.
– Filtered runoff may be returned to storm system via an underdrain and/or infiltrated into surroundings.
Properly Functioning Example:
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Above Ground Practices-Bio-Retention (BR)Properly Functioning Examples:
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Vegetative Practices-Bio-Retention (BR)Standard components • Mulch layer• Filter bed• Inflows• Ponding area• Planned plantings
Optional Components (Design Dependent) • Energy dissipators• Overflow structures (majority of facilities)• Observation wells or
underdrains• Pretreatment (Linear
BMP implementation)
Mulch Layer
PlantingsBerm
Energy Dissipator
Inflow
Overflow Structure
Pond
ing A
rea
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Vegetative Practices-Bio-Retention (BR)
Key Components
Picture: VDEQ Stormwater Design Specification No. 9, Bioretention, Version 1.9, 3/1/11, Figure 9.5 “Typical Detail of Bioretention with Additional Surface Ponding”
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Vegetative Practices-Bio-Retention (BR)
Key Components
Picture: VDEQ Stormwater Design Specification No. 9, Bioretention, Version 1.9, 3/1/11, Figure 9.4 a “Typical Detail of Bioretention Basin Level 1 Design” & Figure 9.4 b “Typical Detail of Bioretention Basin Level 2 Design”
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Vegetative Practices-Bio-Retention (BR)Deficiencies/Conditions Requiring ActionOverflow/Control Structures
Overgrown Vegetation Spalling/deterioration
Sediment/debris Erosion around structure
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Vegetative Practices-Bio-Retention (BR)Ponding Area, including Mulch Layer and Vegetation
Missing, dead, & overgrown vegetation are common issues
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Vegetative Practices-Bio-Retention (BR)Ponding Area, including Mulch Layer and Vegetation Sediment and debris
Other Common Issues Include: • Inadequate mulch layer (<2-3”)• Over-mulching (mounding)• Inadequate ponding depth• Standing water after 48 hours
Check approved site plans for details
Exposed filter fabric
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Vegetative Practices-Bio-Retention (BR)Berm
Erosion and trenching
Other common issues: • Bare spots • Missing/improperly constructed berm
Animal hole
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Vegetative Practices-Bio-Retention (BR)
• 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 plans for specific facility requirements• Missing or inadequate mulch levels are common for this type of
facility
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Vegetative Practices-Bio-Retention (BR)
• Common Remedies– Standing water after 48 hours:
• Underdrain may need to be flushed and re-checked– Rebuild/stabilize any areas with erosion and bare spots:– Cut back overgrown vegetation around facility structures to facilitate
access and proper function• Replace/replant any dead, dying, or missing vegetation per
approved site plan• Remove any non-spec vegetation, especially if it impacts the health
and function of the facility, as designed
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Vegetative Practices-Tree Filters (TF)• Ultra-urban bioretention in a
prefabricated box*, always tied into stormwater infrastructure via an underdrain– Typically implemented in large
areas of imperviousness (parking lots, schools, etc.)
– Plant provides biological pollutant and nutrient uptake
– Sometimes called Tree Box Filters
Properly Functioning Example:
* Note: While the Filterra TF (via Contech) is used here as a convenient example of commonly available/utilized technology, Fairfax County does not endorse any specific tree filter product over another.
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Vegetative Practices-Tree Filters (TF)
Standard Components• Plant (shrub or tree)• Mulch• Filter media• Underdrain• Throat• Overflow structure Overflow Structure
PlantTree Frame and Grate
Flow
Gutter & Curb
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Vegetative Practices-Tree Filters (TF)Key Components (Typical Tree Filter Section View-Filterra 2007)
www.conteches.com
Fairfax County BMP Fact Sheet
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Vegetative Practices-Tree Filters (TF)Deficiencies/Conditions Requiring ActionThroat Opening/Mulch Layer
Common Issues:• Trash, debris, and sediment
accumulation, usually at the throat• Inadequate mulch layer• Missing surge stone at throat• Spalling and deterioration
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Vegetative Practices-Tree Filters (TF)Plants/Vegetation
Dead Vegetation
Missing Vegetation Damaged Vegetation
Overgrown/Crowded
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Vegetative Practices-Tree Filters (TF)Outfall/Overflow Structures
OTHER COMMON ISSUES:
• Blockages• Sediment/debris• Separation/misaligned
joints
Spalling and concrete deterioration
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Vegetative Practices-Tree Filters (TF)
• Common Remedies– Remove all flow blockages as well as any additional trash, debris, and
accumulated sediment– Rebuild/stabilize any areas with erosion and bare spots– 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• Missing or not to spec media and mulch levels are common for this
type of facility• Missing pre-treatment devices, per approved plans
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Vegetative Practices-Tree Filters (TF)
• Common Remedies– Standing water after 48 hours:
• Underdrain may need to be flushed and re-checked– Cut back overgrown vegetation around facility structures to facilitate
access and proper function• Replace/replant any dead, dying, or missing vegetation per
approved site plan• Remove any non-spec vegetation, especially if it impacts the health
and function of the facility, as designed
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Above Ground Facilities-Rooftop Detention (RT)
Is there a need for a short
BREAKor shall we just GET IT DONE?
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Vegetative Practices-Green Roof (GR)• Captures, temporarily stores, &
reduces runoff, while also reducing pollutant loads through biological nutrient uptake– Extensive Roof systems have
shallow soil media (2-6”), with drought tolerant plants such as sedums, and are primarily functional
– Intensive Roof Systems have deeper soil media (6-12”), more extensive plantings, and also act as public green spaces
Properly Functioning Examples:
Intensive Roof SystemIntensive Roof System
Extensive Roof SystemINTENSIVE ROOF SYSTEM
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Vegetative Practices-Green Roof (GR)• Key Components
– Deck layer– Waterproofing layer– Insulation layer– Root barrier– Drainage layer and drainage
system– Root-permeable filter fabric– Growing media– Plant cover– Roof drains– Emergency overflow
VDEQ Stormwater Design Specification No. 5, Vegetated Roof, Version 2.3, 3/1/11, Figure 5.2 “Typical Section-Extensive Vegetated Roof (Source: Northern VA Regional Commission)”
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Vegetative Practices-Green Roof (GR)Key Components
Aluminum curb, filter fabric, & drainage layer(VDEQ Stormwater Design Specification No. 5 Vegetated Roof, Version 2.3, 3/1/11, Figure 5.1 “Photos of Vegetated Roof Cross Sections (Source: B. Hunt, NCSU)
Roof drain Rooftop access (hatch, door, or ladder)
Roof drains and scuppers help to drain off any excess water to avoid accumulation
Multiple downspouts can drain to the GR (from other roof sections)
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Vegetative Practices-Green Roof (GR)
Deficiencies/Conditions Requiring Action– Dead/dying vegetation– Invasive species– Weeds– Waterproof membrane
• Leaks• Cracks
– Clogged roof drains or scuppers
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Vegetative Practices-Green Roof (GR)• 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 plans for specific facility requirements– Rebuild/stabilize any areas with erosion and bare spots– Cut back overgrown vegetation to facilitate proper function
• Replace/replant any dead, dying, or missing vegetation per approved site plan
• Remove any non-spec vegetation, especially if it impacts the health and function of the facility, as designed
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Vegetative Practices-Vegetative Swales (VS)
• Similar to BR in form and function, though typically configured as a shallow linear channel– Primarily stormwater conveyance– Pollutant removal provided via temporary storage/filtration– VS typically lined with turf or other non-turf vegetation to protect
against bank shear stress due to greater runoff velocities
• Check site plans for proper vegetation type
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Vegetative Practices-Vegetative Swales (VS)Standard components • Vegetated banks• Filter media• Inflows• Ponding area• Overflow structureOptional Components (Design Dependent)
• Check dams• Pretreatment• Planned plantings• Underdrains• Observation wells
Overflow Structure
Flow Observation Well
Ponding Area
Vegetated Berm
Flow
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Vegetative Practices-Vegetative Swales (VS)Key Components
Picture: VDEQ Stormwater Design Specification No. 10, Dry Swales, Version 1.9, 3/1/11, Figure 10.2 “Typical Detail s for Level 1 and 2 Dry Swales”
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Vegetative Practices-Vegetative Swales (VS)Key Components
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Vegetative Practices-Vegetative Swales (VS)Deficiencies/Conditions Requiring ActionCheck Dams and Overflow/Control Structure
Undermining/erosion Spalling & deterioration
Sediment and debris
Overgrown vegetation
Internal blockages are also common (not shown)
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Vegetative Practices-Vegetative Swales (VS)Vegetated Banks/Ponding Area/Vegetation
Common Issues (Clockwise from TOP LEFT): • Overgrown vegetation
(see plans, amount varies)• Clogging/poor drainage
(ponding water after 48hrs of dry weather)
• Sediment accumulation (plant growth in gravel often a sign of sediment)
• Erosion, bare spots• (Not shown) Trash & debris
Upper-right photo is from VDEQ Stormwater Design Specification No. 3, “Grass Channels”,
Version 1.9, 3/1/11
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Vegetative Practices-Vegetative Swales (VS)Cleanouts/Observation Wells
LEFT: Broken/damaged RIGHT: Trash/debris
Other Common Issues:• Unable to locate (possibly overgrown vegetation)• Cap stuck, broken, or missing
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Vegetative Practices-Vegetative Swales (VS)
• 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– Rebuild/stabilize any areas with erosion and bare spots:– Cut back overgrown vegetation around facility structures to facilitate
access and proper function• Replace/replant any dead, dying, or missing vegetation per
approved site plan• Mow per plan maintenance guidelines
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Closing Remarks/Questions
Questions?
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Additional Resources
• Fairfax County– Public Facilities Manual (
http://www.fairfaxcounty.gov/dpwes/publications/pfm/)
– Stormwater Management Website (http://www.fairfaxcounty.gov/dpwes/stormwater/)
– Stormwater Best Management Practices Fact Sheets (http://www.fairfaxcounty.gov/dpwes/stormwater/factsheets.htm)
• Virginia Department of Environmental Quality– Stormwater Management Website (
http://www.deq.virginia.gov/Programs/Water/StormwaterManagement.aspx)
– Virginia Stormwater BMP Clearinghouse (http://www.vwrrc.vt.edu/swc/)
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Additional Resources
• Virginia Department of Transportation– N. VA Fairfax & Arlington Counties Permits (
http://www.vdot.virginia.gov/business/fairfax-permits-main.asp)
– Manuals Guides and Informational Instructions (http://www.virginiadot.org/business/manuals-default.asp)
• Includes BMP Design Manual, Drainage Manual, ROW Manual, etc.– Virginia Work Area Protection Manual: Temporary Traffic
Control (http://www.vdot.virginia.gov/business/resources/wztc/Virginia_WAPM_2011_web.pdf)
Additional Information
For additional information, please contact
www.fairfaxcounty.gov/dpwes
39MSMD/DPWES
Department of Public Works and Environmental ServicesMaintenance and Stormwater Management Division
703-877-2800
Stormwater Maintenance Awareness Training
Thanks for attending! Don’t forget to fill out a course evaluation and to pick up your certificate of attendance!