Bioretention Overview

Sustainability for all the places between the buildings.1

Rain Gardens

• Planted, bowl‐shaped area designed to collect and

absorb runoff and reduce polllutants.

2

Rain Gardens

3

Rain Gardens

4

Rain Gardens

5

Stormwater Planters

• Structural container with soil and plants built to collect

and slow runoff and reduce pollutants.

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Stormwater Planters

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Stormwater Planters

Courtesy of Davidsilver of Flickr

Courtesy of Ken Cook of Flickr

8

Swales (aka Bioswales)

• Long, planted, open channel that carries, slows and

absorbs stormwater and filters out pollutants.

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Swales (aka Bioswales)

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Swales

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Swales (aka Bioswales)

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When is a swale really a rain garden?

• When water ponds in the facility instead of flowing

through it:

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When is a swale really a rain garden?

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Green Streets can be Swales

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Vegetated Filter Strip

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Vegetated Filter Strips

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Vegetated Filter Strips

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Vegetated Filter Strips

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Green Streets can be Rain Gardens

• Street designed to capture, absorb and filter runoff using

rain gardens, planters, swales, porous pavement, tree

canopy and other methods.

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Green Streets can be Planters and Tree Canopy

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Green Streets can be Porous Pavement

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The Water Balance Model

Water Quantity Before

40

% e

va

po

rati

on

0.005% runoff

X” r

ain

fall

ye

arl

y a

vg

35

% g

rou

nd

wa

ter

(de

ep

in

filt

rati

on

)23

The Water Balance Model

Water Quantity After

red

uc

ed

eva

po

-ra

tio

n

98% runoff

2%

eva

po

rati

on

Re

du

ce

din

filt

rati

on

X” r

ain

fall

ye

arl

y a

vg

No

infiltra

tion

24

Water Quality Before

Some sediment

25

Water Quality After

Sediment (air particulates)Nutrients

FecesOther debris

Runoff volumes

Sediment/turbidityHydrocarbons

Heavy metals (particles & soluble)Other chemicalsRunoff volume

Sediment/turbidityfertilizerspesticidesherbicides

Runoff volume

26

Water Quality &

Bioretention

Se

dim

en

t/tu

rbid

ity

Hyd

roc

arb

on

sH

ea

vy m

eta

ls (

pa

rtic

les

& s

olu

ble

)O

the

r c

he

mic

als

Ru

no

ff v

olu

me

?

27

Hey! What about detention ponds?

They look pretty green?

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Detention ponds are not LID or… why you must

reduce runoff volume to restore water quality

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Detention ponds

are not low impact development

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Detention ponds

are not low impact development

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Detention ponds

are not low impact development

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Detention ponds

are not low impact development

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Detention ponds

are not low impact development

34

Detention ponds

are not low impact development

35

Detention ponds

are not low impact development

36

Detention ponds

are not low impact development

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Detention ponds

are not low impact development

38

Runoff Volume & Duration

from a Watershed Perspective

39