Bioretention Matt Scharver Northeast Ohio Regional Sewer District - - PowerPoint PPT Presentation

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Bioretention Matt Scharver Northeast Ohio Regional Sewer District - - PowerPoint PPT Presentation

Nov 25, 2022 139 likes •483 views

Bioretention Matt Scharver Northeast Ohio Regional Sewer District #ProjectCleanLake Stormwater Management Training for MS4 Municipal Employees Training Session Agenda Pre-Training Survey Presentation & Site Visit

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#ProjectCleanLake

Bioretention

Matt Scharver Northeast Ohio Regional Sewer District

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#ProjectCleanLake

  • Training Session Agenda

– Pre-Training Survey – Presentation & Site Visit – Post-Training Survey

  • Today’s Selected SCM: Bioretention

– Design features – Construction pitfalls – Operation & Maintenance activities

Stormwater Management Training for MS4 Municipal Employees

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Bioretention

Stormwater Control Measure

Bioretention/Bioswale

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Bioretention Concept

Overflow to local sewer or environment

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Bioretention/Rain Garden Design

Key Design Considerations/Features

  • Hydrology
  • Inlets and Outlets
  • Materials
  • Vegetation
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Bioretention / Rain Gardens

  • Uses soil media, mulch, and

vegetation to reduce runoff and treat stormwater

  • Treatment occurs through:

– Sediment settling – Microbial breakdown – Nutrient uptake by plants – Infiltration – Detention

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Bioretention/Rain Garden

Design Basics

  • Designed to treat the Water Quality

Volume

– Water Quality Volume = runoff from the first ¾ inch of rainfall – Drain down in a day’s time – May be constructed online or offline

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Bioretenion/Rain Garden

Inlets

Distributes runoff into bioretention via:

– Curb cuts – Trench Drain – Grass swales or berms

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Bioretention/Rain Garden

Pre-Treatment

Reduce sediment loads

– Hydrodynamic separators – Grass inlets – Forebays

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Pea-gravel Sand Bio-soil Mulch

#57 Gravel

Underdrain

Clean Out

Underdrain

Bioretention/Rain Garden

Treatment System

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Bioretention

Ponding Depths Should be 12 inches between the top of the bed and the top of the overflow

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Bioretention Concept

Overflow to local sewer or environment

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Bioretention/Rain Garden

Mulch

  • Double shredded hardwood
  • 3” layer
  • Keeps weeds down
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Bioretention/Rain Garden

Soil Media

  • Loamy Sand 2-4 feet
  • By Volume

– 75% Sand (AASHTO M-6 OR ASTM C-33)

– 15% fines (Native soil) – 10% Organic Matter (Compost)

  • pH 5.2-8.0
  • Phosphorus 15-60 mg/kg
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Bioretention

Filter Layer

  • Prevents the planting soil from

moving into the stone

  • 3 inches of sand over 3 inches of

pea gravel #78

  • NO FILTER FABRIC
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Bioretention

Gravel Layer/Underdrains

  • May or may not be designed with

underdrains

  • 10-12 inch gravel bed of #57 washed

stone

  • Should be 3 inches of gravel above

and below underdrain tile

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Bioretention/Rain Garden

Vegetation

  • Tolerate temporary inundation
  • Natives or cultivars depending on look

and function

  • Can include trees and shrubs
  • Best to plant in deliberate patterns

and plants of the same type together to better identify weeds from intended plantings

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Bioretention/Rain Garden

Construction

  • Pre-Construction Meeting
  • Timing
  • Excavation
  • Structural Components
  • Planting
  • Mulching
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Bioretention/Rain Garden

Construction - Timing Constructed AFTER the upstream drainage area is stabilized

– Avoid sealing off the native soils – Avoid fines contamination

  • f the bio-soil mix
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  • Ideally construct during dry weather
  • Do not leave open for extended

periods of time

Bioretention/Rain Garden

Construction - Timing

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Bioretention/Rain Garden

Construction - Excavation Properly sized equipment

– Work from the sides – Avoid bottom compaction – Excavate in steps

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  • Sides of cell vertical
  • Bottom of cells level
  • Use bucket teeth to

scarify sides and bottom of cell

Bioretention/Rain Garden

Construction - Excavation

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Bioretention/Rain Garden

Construction - Excavation

  • Erosion and Sediment control critical
  • Keep practice “off-line” for as long as

possible

  • Stabilize side-slopes ASAP
  • Protect bio-soils with sheeting or geo-

textile

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Bioretention/Rain Garden

Structural Components Inlet/outlet elevations critical to function

– Water needs to get into the practice – Water needs to pond in the practice – Outlets will be elevated – Underdrain may be elevated to encourage infiltration – Cleanouts should be provided

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What’s wrong in the photo?

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Bioretention/Rain Garden

Maintenance Key points…

  • “Reading the practice”
  • Interpreting flow paths
  • Listing of major maintenance

components

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Bioretention/Rain Garden

Maintenance

Key points…

  • Shredded vs. pine bark mulch
  • Routine vs. non-routine maintenance
  • Vegetation maintenance
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Bioretention/Rain Garden

Maintenance Key points…

  • Standing water, vegetation health,

sediment & erosion

  • Note sediment accumulations
  • Note smaller orifice & outfall sizes
  • Note shape of bioswale… problem?
  • Note underdrain & inlet configuration
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Bioretention/Rain Garden

Maintenance Final tips…

  • Refer to individual SCM project O&M

Manual

  • Obtain copies of As-Built Plans
  • Maintain accurate map of feature’s

designed & constructed drainage area

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Field Site: place site image here

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Questions?