Making Bioretention Work

Sustainability for all the places between the buildings.

Green Girl Land Development Solutions

• Certified Woman Owned Business

• Sole Proprietorship

• NOT Design & Permitting

• Technical Assistance & Project Based Mentoring

Agenda

• OVERALL MESSAGE: How to create more effective facilities (ones that protect your watershed) that are less costly and lower maintenance!

• Top 10 Common Mistakes to Avoid: Considerations for planning, design, construction & maintenance of common bioretention components

1. Suitable Infiltration Areasare NOT found on a NRCS soils map

You must test your soil where bioretention is going to be located

2. Flow-Through (Lined) Facilities are NOT nearly as good as infiltration facilties

43

Lined on three sides with an impermeable liner =

“Flow-Through”

Detention Basin & Flow Through Facilities Results

from a Watershed Perspective

3. Don’t Over-engineer It

31

OSU Extension - Sea Grant OregonChoose the Right Rain Garden Wizard

Find out where you should and shouldn’t infiltrate!http://extension.oregonstate.edu/stormwater/

choose-right-rain-garden

4. Consider Contribution Area Don’t Underestimate Flows or WQ Impacts

4. Consider the Contribution AreaDon’t Underestimate Flows or WQ Impacts

• Most gravel roads and parking lots are impervious

4. Consider Contribution Area

• Copper• Zinc (Galvanized)• Iron (Rust=iron)(in roofs &

downspouts)• What else is coming

from YOUR site?

4. Consider Contribution Area

What pollutants are intentionally designed

into your facility?

5. Undercutting can be protected against

• A curb or impermeable liner (vertically installed) would have prevented damage to the adjacent impervious pavement at this inlet

6. Settle out Sediments Before Bioretaining

And make it easy on the maintenance folks

• Rip rap makes it difficult to remove sediment from and re-suspension is more likely than in sumped structures (shown previously)

7. Help Water Make 90 degree turns

Depressed gutter

Depressed gutter

Make curb cut at least a shovel wide or wider

Make curb cut at least a shovel wide or wider

Round the corners

Round the corners

7. Help Water Make 90 degree turns

8. Protect Against Erosionwith overland flow

8. Protect Against ErosionRounded Rock Doesn’t Adequately Slow Water

• Use crushed, angular rock instead

8. Protect Against ErosionDon’t plant vegetation in rows parallel to flows

8. Protect Against Erosionbut don’t use the dry creek bed look

• To maximize water quality treatment, plants must be in the bottom, where the most polluted “water quality” storm flows the most often.

9. Design to pond water for better WQ

10. Choose Vegetation CarefullyUse a diversity of species… or not

10. Choose Vegetation CarefullyUse Native Vegetation (not “harmless” non-

natives)

10. Choose Vegetation CarefullyUse Native Vegetation (not “harmless” non-

natives)

11. One last best practiceHave fun!

Thank You for Coming Today!

Sustainability for all the places between the buildings.

PollutionPollution

Bioretention is NOT a Silver Bullet

And can make things worse.There’s no substitute for SOURCE CONTROL

PollutionPollution

Some Common Pollutants

Sediment (air particulates)Nutrients

FecesOther debris

Runoff volumes

Sediment/turbidityHydrocarbons

Heavy metals (particles & soluble)Other chemicalsRunoff volume

Sediment/turbidityfertilizerspesticidesherbicides

Runoff volume

Bioretention& Development

Sediment (

air part

icula

tes)

Feces

Other d

ebris

Runoff volu

me

Sed

imen

t/tu

rbid

ity

Hyd

rocarb

on

sH

eavy m

eta

ls (

part

icle

s &

solu

ble

)O

ther

ch

em

icals

Ru

noff

volu

me

Sediment/turbidity

fertilizers

pesticides

herbicides

Runoff volume

?

?

?