what should associations know about stormwater management? · • after 2007, envirionmental site...
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What Should Associations Know About StormwaterManagement?
Matthew WatersCity of Annapolis Stormwater Engineer
How To Determine If You Have SWM?
• Know when your community was constructed• If it was before 1985, it is not likely• Between 1985 and 2007, likely a Best Management Practice (BMP)• After 2007, Envirionmental Site Design (ESD) and/or BMP
• Look up community information• Try to get the plans for the development• Know what you own and if there are any easements• There might be a maintenance agreement attached to the land records
• Talk to your government!
Pre‐Inspection Checklist
• Know some common infrastructure names and terms• Know what type of practice you have or have plans if possible• Have a flashlight and camera• Have good sturdy and waterproof shoes on• DO NOT GO INTO STRUCTURES OR PIPES!
Typical Infrastructure and TermsStructures and Converyances:• Inlet• Manhole• Junction Box• Riser• Headwall• Endwall• Stormdrain Pipe• Swale
Terms:• Inflow – where runoff enters a practice
• Outfall – where runoff leaves a practice
• Spillway – area where SWM Practice can overflow after a stormevent is reached
• Forebay – Pretreatment area• Side Slopes – sides of practice• Embankment – downstream end of SWM practice
Inlets
Manholes
Junction Boxes
Riser – Concrete or Metal
Headwalls and Endwalls
Headwalls and Endwalls
Embankment
Forebay
Typical Places for Inspection
• Check your inflows• Check the pipe joints if concrete or check for rust if metal• Check for a stability around the inflow
• Check your outfall• Similar checks to inflows
• Check your Riser Structure• No leaks or debris inside or around the structure
• Check your Embankment• Seepage is bad!
Common Issues
• Sediment and debris build up• Erosion • Clogged media/filter• Sink holes• Scour• Ponding• Overgrowth• Issues with pipes
Maintenance to look for!
Debris on Riser
SWM BMPs – Typical Maintenance
• Trash Removal.• Annual mowing of embankment and maintenance access.• Erosion repair.• Animal removal.• Unclogged low‐flow orifice or remove debris on trash rack• Vegetation maintenance – No woody vegetation on or near toe of embankment and principal spillway.
• Sediment removal from the forebay when 50% of capacity is lost.
SWM BMPs – Major Maintenance
• Sinkholes from pipe failures like gaps at the joints of the pipes.• Water seeping into riser structure.• Erosion at the outfall of a pipe.• Major sedimentation in practice.
Erosion at Outfall!
Best Management Practices and Environmental Site DesignsTypes of BMPs• Stormwater Ponds• Stormwater Wetlands• Stormwater Infiltration• Stormwater Filtering Systems• Open Channel Systems
Types of ESDs• Alternative Surfaces• Non‐structural Practices• Micro‐Scale Practices
BMP – Stormwater Ponds
• SWM practices that have a permeant pool of water.• 5 variations of SWM Ponds.• Elements may include Inflow, Forebay, Riser, Spillway, Endwall, Low‐Flow Orifice.
• Should have a fence around it.
SWM Ponds
SWM Ponds
SWM Ponds
SWM Ponds
SWM Pond
BMP – Stormwater Wetlands
• SWM practices that create a shallow wetland• 4 variations of SWM Wetlands• Needs to maintain a 30 day drought• Vegetation is very important for success• Elements may include Inflow, Forebay, Riser, Spillway, Endwall, Low‐Flow Orifice
• Main difference from Ponds – shallow water levels and not deep permenant pools
SWM Wetlands
SWM Wetlands
SWM Wetlands
SWM Wetlands
BMP – Stormwater Infiltration
• SWM practices that capture runoff and allow for infiltration.• 2 variations of SWM Infiltration• Need to have good soils.• Elements may include Inflow, Forebay, Riser.
SWM Infiltration
SWM Infiltration
BMP – Stormwater Filtering Systems
• SWM Practices that capture runoff and treat by filtering through a media like sand, organic material, soil.
• 6 variations of SWM Filtering Systems.• Can be as an inline practice or offline practice.• Elements may include inflow, forebay, inlets, underdrains, spillways.• Landscaping and vegetation is very important to success of practice
SWM Filtering System
SWM Filtering System
SWM Filtering System
SWM Filtering System
SWM Filtering System
SWM Filtering System
BMP – Open Channel Systems
• Vegetated open channels that capture and treat runoff with dry or wet cells formed by check dams.
• 2 variations: Wet Swale and Dry Swale• Elements may include inflow, forebay, inlets, underdrains, check dams• Need to have flat slopes and low velocities in swale.
Best Management Practices and Environmental Site DesignsTypes of BMPs• Stormwater Ponds• Stormwater Wetlands• Stormwater Infiltration• Stormwater Filtering Systems• Open Channel Systems
Types of ESDs• Alternative Surfaces• Non‐structural Practices• Micro‐Scale Practices
ESD ‐ Alternative Surfaces
• 3 variations – Green Roofs, Permeable Pavements, Reinforced Turf• Practices that reduce impervious area on site• Green Roof maintenance includes weeding and ensuring plantings are established
• Permeable Pavements maintenance includes sweeping and vacuuming
• Reinforced Turf maintenance includes mowing and ensuring turf is established
Non‐structural Practices
• 3 variations – Sheetflow to Conservation Area, Rooftop and non‐rooftop disconnections
• Practices that direct runoff away from traditional storm drain systems.• Maintenance for all non‐structural practices include mowing and ensuring the vegetation is established.
Micro‐Scale Practices
• Practices that capture and treat a small drainage areas.• Maintenance very similar to BMPs• 9 main categories including:
Rain Water Harvesting Submerged Gravel Wetlands Landscape Infiltration Infiltration Berms Dry Wells
Micro‐Bioretention Rain Gardens Swales Enhanced Filters
ESD Micro Scale Practices
ESD Micro Scale Practices
ESD Micro Scale Practices
ESD Micro Scale Practices
ESD Micro Scale Practices
ESD Micro Scale Practices
ESD Micro Scale Practices
Where can I find more information?
• MDE Stormwater Manual ‐https://mde.maryland.gov/programs/water/stormwatermanagementprogram/pages/stormwater_design.aspx
• City of Annapolis SWM ‐ https://www.annapolis.gov/450/Stormwater‐Management
• Montgomery County RainScapes Program ‐https://www.montgomerycountymd.gov/water/rainscapes/
• Anne Arundel County SWM Program ‐ https://www.aacounty.org/services‐and‐programs/stormwater‐management‐manual
• Watershed Stewards Academy – www.AAWSA.org
References
• Inlet Image ‐https://safety.fhwa.dot.gov/local_rural/training/fhwasa09024/
• MDSHA Detail for Junction Box• Metal Riser Image ‐https://www.montgomerycountymd.gov/water/stormwater/major‐projects.html
• 2000 MDE SWM Manual Volumes 1 and 2• Chapter 3 is all about BMPs• Chapter 5 is all about ESDs
