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Planning Green Infrastructure Implementation

Imagine the result

Hazem Gheith, Ph. D., P.E.

OWEA April 5, 2012

Planning Green Infrastructure Implementation, OWEA April 5, 2012 © 2012 ARCADIS

Imagine the result 2

Learning Objectives

• Recognize function, types, challenges

and opportunities of Green

Infrastructure technologies in urban

area

• Recognize factors affecting the

selection of GI technologies to meet

planning objectives

• Identify datasets required for planning a

successful GI implementation program

• Understand the role of hydrology and

hydraulics modeling in assessing the

various benefits of GI



Agenda • Green Infrastructure technologies

Overview

• Factors Affecting the Selection of GI

Technologies and Required Resources

• Careful Considerations on the

Hydrology and Hydraulic Analysis of GI

Units

• Planning Green Infrastructure

Implementation Example

Imagine the result


4

Rainfall Receiving

Waters

Evapotranspiration

Infiltration

Natural Storage

GI Units

Collection

System

Green Land/

natural

conditions

Urbanized land

Planning Green Infrastructure Program in Urban Area

A

B

C



Benefits of Green Infrastructure

• Reduced runoff volume means less potential for flooding and less load on stormwater or combined flow collection systems.

• Reduced velocities and peak flows protects the integrity of streams banks and reduces the occurrence of CSOs.

• Reduced pollutant loads through mitigation at the source. Leads to more streams and rivers meeting water quality standards.

• Increased recharge to groundwater reservoirs.

Imagine the result


6

Rainfall Receiving

Waters

Alt 1 GI Units

Collection

System Urbanized land

Successful GI Plan

Alt 2 GI Units

Alt 3 GI Units

(1) Maximize the usage of GI

units by careful selection of

location, careful sizing, and

maximizing inflows)

Improved Condition

(2) Achieve WWF

Control Goal at key

points in the

collection system

Gravel

Soil

Water

Infiltration

Evaporation/Transpiration Runoff Overflow

Drain

dW

dS

dG



Possible Units for Heavy Urban Area

• Green Roofs

• Bioretention Cells

• Rain Gardens

• Urban Planters

• Porous Curbs and Gutters

• Subsurface Detention

• Bioswales

• Permeable Streets and Parking

• Rain Barrels/Cisterns

• Downspouts Disconnection

(combined flow systems)

Imagine the result


8

Green Roofs • Basic function: Evapotranspiration

• Application: Vegetation on roofs

• Location: Preferably commercial

and industrial roofs for large size

and low slope

• Limitations

• Requires active involvement of

private sector

• Requires load-bearing capacity

and leak resistance

• Limited storage capacity in

plantation soil

• No infiltration to groundwater

http://www.answers.com/topic/green-roof

Gravel

Soil

Water

Infiltration


Drain

dW

dS

dG

//upload.wikimedia.org/wikipedia/commons/3/39/Nor%C3%B0rag%C3%B8ta,_Faroe_Islands_(2).JPG

Imagine the result


9

Bioretention Cells • Basic function: Storage (infiltration)

• Application: Convert an impervious

surface to vegetated pervious

surface and amend natural soil with

layers of porous media

• Location: Street intersections

upstream storm inlets. Convert

portion of the side walk or parking.

• Limitations

• Special design for inlet, overflow

and under drains

• Several units for measurable

stormwater reduction in medium to

large storms

• Requires deep GW table

Gravel

Soil

Water

Infiltration


Drain

dW

dS

dG

Imagine the result


10

Rain Gardens • Basic function: Storage (infiltration)

• Application: Excavate to amend

natural soil with layers of porous

media. Captured water infiltrates to

groundwater between storms.

• Location: Right of ways. Work

perfect if put on series (train).

• Limitations

• Special design for inlet and

overflow

• Small – requires several units for

measurable stormwater reduction

in medium to large storms.

• Requires naturally permeable soil

http://www.clemson.edu/extension/county/greenville/programs/horticulture/ra

ingarden.html

Gravel

Soil

Water

Infiltration


Drain

dW

dS

dG

http://www.clemson.edu/extension/county/greenville/programs/horticulture/raingarden.html

http://www.clemson.edu/extension/county/greenville/programs/horticulture/raingarden.html

Imagine the result


11

Urban Planters • Basic function: Evapotranspiration

(infiltration)

• Application: Replace large

impervious area or poorly

vegetated area with vegetation,

without excessive excavation

• Location: Backyards, interception

of downspouts, and street medians

• Limitations

• Limited storage capacity in

planter soil

• Requires re-grading to collect

runoff into the planters Gravel

Soil

Water

Infiltration


Drain

dW

dS

dG

Imagine the result


12

Porous Curb and Gutter • Basic function: Storage (infiltration)

• Application: Replace conventional

curb and gutter with porous

surface above a 2 to 3-foot gravel

layer for storage and infiltration.

• Location: Neighborhood and main

roads with low slop

• Limitations

• High maintenance to vacuum

fine-grain soils

• Tree roots

• No evapotranspiration

Gravel

Porous Surface

Water

Infiltration


Drain

dW

dS

dG

Imagine the result


13

Subsurface Detention • Basic function: Storage (infiltration)

• Application: Excavate and cover a

subsurface concrete structure with

a gravel bed

• Location: Low traffic alleys at its

intersection with streets

• Limitations

• Requires load bearing capacity

• Requires low traffic conditions

• No evapotranspiration

Gravel

Porous Surface

Water

Infiltration


Drain

dW

dS

dG

Imagine the result


14

Bioswales • Basic function: Infiltration (storage)

• Application: Long shallow surface

channels with vegetated surface.

Check dams to slow flow and

increase storage.

• Location: Roadsides with no curbs

and gutters

• Limitations

• Inconvenience to public

• Potential flooding

Gravel

Soil

Water

Infiltration


Drain

dW

dS

dG

Imagine the result


15

Permeable Parking and Streets • Basic function: Infiltration (storage)

• Application: Replace conventional

paving material with porous surface.

• Location: Large commercial parking

side of low traffic streets

• Limitations

• Good for low traffic areas

(parking lots, sidewalks, alleys)

• High maintenance to vacuum

fine-grain soils

• Limited storage and no

evapotranspiration

Gravel

Porous surface

Water

Infiltration


Drain

dW

dS

dG

Imagine the result


16

Rain Barrels • Basic function: Rainwater Harvesting

• Application: Collect roof runoff by

intercepting downspouts.

• Location: Residential houses

• Limitations

• Requires active involvement of private

sector (pluming and dewatering)

• Limited Storage and no

evapotranspiration or infiltration

Gravel

Soil

Water

Infiltration


Drain

dW

dS

dG



Downspout Disconnections • Basic function: Infiltration

(evapotranspiration)

• Application: Disconnect

downspouts from discharging

directly to curb lines or

combined sewers.

• Limitations

• Requires active involvement of

private sector

• Potential for inconvenient ponding

between storms

• Limited Storage

Imagine the result


18

GI Units Summary

GI Type Evapo-

transpiration Storage Infiltration Limitations

Green Roof High Low None Load-bearing capacity of roofs. Leak resistance. Large commercial or

industrial roofs. Private sector involvement.

Urban Planters High Low Medium Limited storage capacity in planter soil. Limited size. Private sector

involvement.

Rain Gardens Low High Medium Requires naturally permeable soil, careful cultivation while native plants

initially become established.

Bioretention

Cells Low High Medium

Requires specially-designed inlet, overflow, and underdrain structures. Best

performance when GWT is more than 4 feet below base.

Porous

Pavements &

Curbs

None High Medium Requires low traffic areas with mild slopes. Requires high maintenance to

vacuum fine-grain soils. More depth is hindered by conflicts with utilities.

Bioswales Medium High High Requires mild slope (<6%). Best when serving small acreage area (<15 acres).

Requires larger easements than normal storm pipes.

Rain Barrels,

Cisterns None High None

Useful only if large number of neighborhood residents participates in the

program. Some maintenance is required. Freezing conditions is a problem.

Downspout

Disconnections Medium Low High

Good if local soil is permeable (2 ft+). Better if surface slope is low.

Infiltration might show up in the foundation drain. Inconvenient ponding

may occur.

Imagine the result


19

GI Challenges / Concerns

• Capital Costs may be comparable to

Grey Infrastructure

• Relatively short history of operations

• Performance in terms of meeting

CWA is somewhat uncertain

• Maintenance requirements

• Public commitment

• Performance impacted by local

conditions (soils, climate, rainfall, etc.)

http://www.raingardennetwork.com/rgphotosE5.htm

http://www.raingardennetwork.com/rgphotosE5.htm

Imagine the result


20

Urban System Challenges

• Unique challenges:

• Limited open space

• Expensive urban lands

• Small-scale projects

• Existing utility conflicts

• Unique opportunities

• Coordination with other construction (redevelopment, roads, etc.)

• Coordination with existing parks

• Increase neighborhood life conditions

http://www.portlandonline.com/bes/index.cfm?a=77074&c=45435#photos

http://www.portlandonline.com/bes/index.cfm?a=77074&c=45435




Overview


Technologies and Required

Resources


Hydrology and Hydraulic Analysis of

GI Units





• Factors related to the objective of the

GI program

• Pollutant removal

• Stormwater volume reduction

• Peak flow reduction

• Factors related to construction and

maintenance

• Utilities conflict, departments coordination, etc.)

• Maintenance costs

• Factors related to drainage

configuration

• Subsurface infrastructure (increasing RDII?)

• Factors related to ownership

• Public versus private properties

Factors Affecting GI Technology Selection



Factors Affecting GI Technology Selection

• Factors affecting infiltration capacity

• Permeability of local area natural soils

• Fluctuation in groundwater table

• Factors affecting the

evapotranspiration capacity

• Climatic conditions

• Local vegetation intensity and species

• Factors affecting storage capacity

• Topography and surface slope

• Availability of open spaces



Required Resources

GIS Layers

• Topography/contour lines

• Collection system network

• Streams and water bodies

• Storm (and combined) sewers

• Storm inlet points (catch basins)

• Soil maps

• Land use and impervious and

pervious areas configuration

• Orthophoto layers (Internet

Resources)



Required Resources (continued) Field Data

• Identify key hydrology and

hydraulics features of the system

• Opportunities analysis

• Open space

• Public properties (schools, parks,

street medians, etc)

• Condition of streets, curbs,

and alleys

• Wet weather condition

• Drainage quality



Required Resources (continued) Hydrology and Hydraulics Evaluation Tools:

• Urban Complex hydraulic components

• Surcharged pipes/culverts

• Backwater effects

• Pump stations

• Weirs/movable gates

• Green Infrastructure Units Complex hydraulics

• Infiltration process in layered medium

• Overflow and under drain structures

• Storage/evapotranspiration/infiltration processes

• Back to back storms

• Requires dynamic wave calculations

• SWMM family, InfoWorks, Mike Urban, etc.




Overview



Resources



GI Units





Catchment Surface Runoff Challenges

Sample area with Catch

basins at the intersection

• Runoff surfaces

• Garage roofs

• Lawns

• House roofs

• Drive ways

• Side walks

• Alleys

• Parking lot

• Street

1: Delineation at MH level

2: Storm Inlet level

3: Subarea level



Runoff Input Parameters

• Area

• % Impervious

• Width

• Slope

• Manning

• Depression

Storage

• Infiltration

• % Routed

Challenges with MH Catchment Level

Some Challenges

• One slope value for all

features within the

catchment

• One abstraction value for

all impervious surfaces

• One width parameter for

the sheet-flow calculation

for all subareas (pervious

and impervious features)

• Etc.

Impervious Pervious

Receiving Manhole



Traditional Delineation • One flow meter per several catchments. May achieve good

calibration - good for evaluating downstream controls (grey).

• Uncertain about runoff distribution at catchment level and inside.

20%Error:

ISE rating

ISE

R²

SEE

LSE

LSE dim

RMSE

RMSE dim

0053C2782:0053C0603

Excellent

2.32

0.938

0.576

22.2

2.59

3.41

0.19

0

1

2

3

4

5

6

7

8

9

10

11

12

0 2 4 6 8 10 12

Computed vs Observed Max Flow (mgd) at Link 0053C2782:0053C0603

Com

pute

d M

ax F

low

(m

gd)

Observed Max Flow (mgd)



Challenges with Inflows into GI Units

Backyard Planters

• Garage roofs

Train of Rain Gardens

• Garage and House roofs

• Lawns

• Part of the Street (Alleys)

• Inflow from US Rain Garden units

Porous Curb and Gutter

• All subareas, except houses DC to combined pipes

Bioretention Cells


Green Roofs

• Targeted Roof only

Permeable Parking

• Building roof

• Parking lot

Permeable Street




Enhanced Delineation

Lawns

Drive

Ways /

Streets

House

Roofs

(discon.)

Combined

Manhole

Storm

Inlet

House

Roofs

(to street)

Commerc

ial roof Parking

House

Roofs

(connect.)

Outfall

Split the catchment into subareas

representing the true runoff

configuration

• House Roofs

• Discharge onto lawns

• Discharge to the curb line

• Directly connect to combined

sewer (combined flow systems)

• Commercial roofs discharge to

parking lots

• Parking Lots discharging to collection

system

• Drive ways, alleys, and street

discharge to storm inlets

Alleys



Enhancements Improves Flow Prediction • Several parameters are known (roofs slope, roofs flow length, roofs

depression storage, streets and alley slopes and flow length, etc.)

• Faster calibration since only few parameters are up for calibration

20%Error:

ISE rating

ISE

R²

SEE

LSE

LSE dim

RMSE

RMSE dim

0053C2782:0053C0603

Excellent

1.76

0.964

0.436

12.7

1.12

2.58

0.144

0

1

2

3

4

5

6

7

8

9

10

11

12

13

0 2 4 6 8 10 12

Computed vs Observed Max Flow (mgd) at Link 0053C2782:0053C0603

Com

pute

d M

ax F

low

(m

gd)

Observed Max Flow (mgd)

Imagine the result


34

Better Understanding of Flow Configuration

0

0.5

1.0

1.5

2.0

2.5

3.0

3.5

5AM

Jun 14 Sat 2008

6AM 7AM 8AM 9AM

Link 0086C0132:0086C0133

Flo

w (

mgd)

Date/Time

DoeAlley_NewDelineation 0086C0132:0086C0133 DoeAlley_Recal_Hazem



Educated Prioritization of Catchments for GI Implementation • Locate inlet catchments

with higher flow

contribution

• Select optimum location

for GI units to maximize

benefit

• Achieve control goal at

much less cost




Overview



Resources



GI Units


Example

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37

H/H Analysis of GI Units Example: Combined flow collection basin.

Use GI units to reduce volume and peak

flow.

• Based on GI unit type, it can be placed

at certain locations within the study

area. Hence, they will impact different

portions of the runoff catchment.

• It is important to have a reasonably

detailed representation of hydrology

features of the runoff catchment.



Example H/H Analysis of GI Units

Total catchment area = 5 acres

• Roof tops = 1.5 acres

• 0.9 acres: roofs with disconnected

downspouts

• 0.3 acres garages

• 0.6 acres houses

• 0.15 acres: roofs discharge to street

• 0.15 acres: roof commercial discharges to

parking area

• 0.3 acres: roofs directly connected to

combined sewers

• Pervious lawns = 2.6 acres

• 1 acre backyards

• 1.6 acre side and front yards

• Impervious ground surface = 0.9 acres

• 0.25 acres parking lots

• 0.65 acres street and driveways

Back

yards

(1 ac)

Side /

Front

(1.6

ac)

Drive

Ways /

Streets

(0.65 ac)

Garage

(0.3 ac)

Houses

(disconn.)

(0.6 ac)

Combined

Manhole

Storm

Inlet

Houses

(to street)

(0.15 ac)

Commerc

ial roof

(0.15 ac)

Parking

(0.25

ac)

Houses

(connect.)

(0.3 ac)

Outfall



Example H/H Analysis of GI • Test design storm

• 24-hours SCS Type II (2.17 in)

• Evaporation rate = 0.1 in/day

• Natural soil infiltration parameters:

(Binnington)

• Permeability = 0.06 in/hour

• Suction head = 11 inches

• Moisture deficit = 0.1

• Results for base Condition:

• Peak flow = 2.7 MGD

• Runoff volume = 0.14 MG



Planters • Assumptions:

• Location: Each backyard

(26 x 10’ x 10’)

• Configuration: 6” of vegetated soil

• Outflow Peak flow = 2.59 MGD (-5.6%)

• Outflow Volume = 0.14 MG (-1.4%)

Back

yard

Side /

Front

Yard

Drive

Ways /

Streets

Garage

Houses

(disconn.)

Combined

Manhole

Storm

Inlet

Houses

(to street)

Commerc

ial roof Parking

Houses

(connect.)

Outfall

Planters



Green Roof • Assumptions:

• Location: Commercial roof (0.25 acres)

• Configuration: 4” of vegetated soil

• Peak flow = 2.63 MGD (-4.1%)

• Volume = 0.13 MG (-6.3%)

Back

yard

Side /

Front

Yard

Drive

Ways /

Streets

Garage

Houses

(disconn.)

Combined

Manhole

Storm

Inlet

Houses

(to street)

Parking

Houses

(connect.)

Outfall

Comm.

roofs



Rain Gardens • Assumptions:

• Location: ROW (2 trains, 6 x 3’ x 10’)

• Configuration: 18” gravel topped

with 12” of vegetated soil.

• Peak flow = 2.72 MGD (-0.6%)

• Volume = 0.14 MG (-3.6%)

Back

yard

Side /

Front

Yard

Drive

Ways /

Streets

Garage

Houses

(disconn.)

Combined

Manhole

Storm

Inlet

Houses

(to street)

Commerc

ial roof Parking

Houses

(connect.)

Outfall

Street

RG



Bioretention Cells • Assumptions:

• Location: Road intersection

(2 sides, 6’ x 30’ each)

• Configuration: 18” gravel topped with 6” of

vegetated soil, topped with a 12” detention

• Peak flow = 2.74 MGD (-0.07%)

• Volume = 0.14 MG (-1.4%)

Back

yard

Side /

Front

Yard

Drive

Ways /

Streets

Garage

Houses

(disconn.)

Combined

Manhole

Storm

Inlet

Houses

(to street)

Commerc

ial roof Parking

Houses

(connect.)

Outfall

BRC



Porous Curb & Gutter • Assumptions:

• Location: Road side (2 x 2.5’ x 1400’)


with 6” of permeable concrete

• Peak flow = 1.41 MGD (-49%)

• Volume = 0.13 MG (-7.8%)

Back

yard

Side /

Front

Yard

Drive

Ways /

Streets

Garage

Houses

(disconn.)

Combined

Manhole

Storm

Inlet

Houses

(to street)

Commerc

ial roof Parking

Houses

(connect.)

Outfall

P

C

G



Permeable Pavement - Street • Assumptions:

• Location: Public street (0.65 acres)


with 3” of permeable surface

• Peak flow = 0.76 MGD (-72.1%)

• Volume = 0.07 MG (-51.1%)

Back

yard

Side /

Front

Yard

Permeable

Streets

Garage

Houses

(disconn.)

Combined

Manhole

Storm

Inlet

Houses

(to street)

Commerc

ial roof Parking

Houses

(connect.)

Outfall

Drive

ways



Permeable Pavement - Parking Lot • Assumptions:

• Location: Commercial parking (0.25 acres)


with 3” of permeable surface

• No under drain assumed

• Peak flow = 2.5 MGD (-8.6%)

• Volume = 0.12 MG (-15.6%)

Back

yard

Side /

Front

Yard

Drive

Ways /

Streets

Garage

Houses

(disconn.)

Combined

Manhole

Storm

Inlet

Houses

(to street)

Commerc

ial roof Parking

Houses

(connect.)

Outfall



Rain Barrels • Assumptions:

• Location: All garages and houses

(56 roofs x 2 barrels per roof)

• Configuration: 60 gallons barrels (24” x 39”)

• Peak flow = 2.73 MGD (-0.3%)

• Volume = 0.14 MG (-4.3%)

Back

yard

Side /

Front

Yard

Drive

Ways /

Streets

Garage

Houses

(disconn.)

Combined

Manhole

Storm

Inlet

Houses

(to street)

Commerc

ial roof Parking

Houses

(connect.)

Outfall

RB

RB

RB

RB

Imagine the result


48

Design Storm Summary Results

GI Units

Design

Storm

Peak Flow

Reduction

Design

storm

Volume

Reduction

Green Roof 4.1% 6.3%

Planters 5.6% 1.4%

Rain Gardens 0.6% 3.6%

Bioretention Cells 0.07% 1.4%

Porous Curb and

Gutter 49% 7.9%

Porous Pavement

(Street) 72.1% 51.3%

Porous Pavement

(Parking Lot) 8.6% 15.6%

Rain Barrels 0.3% 4.3%

Imagine the result


49

Typical Year Storms Results

GI Units

Typical Year

Volume

Removed

(gallons)

Typical Year

Percentage

Volume

Reduction

GI Cost

Dollar amount

per gallon

removed

Green Roof 138,000 7.8% $99,186 $0.71

Planters 27,000 1.5% $9000 $0.33

Rain Gardens 116,000 6.6% $14400 $0.12

Bioretention Cells 88,000 5% $10,800 $0.12

Porous Curb and

Gutter 419,000 23.7% $252,000 $0.50

Permeable Street 1,151,000 65% $318,860 $0.28

Permeable Parking 370,000 20.9% $108,900 $0.29

Rain Barrels 163,000 9.2% $36,960 $0.23



Example H/H Analysis of GI

Consideration on the results

• Careful field investigation and hydrology and

hydraulics analysis are keys for a successful green

infrastructure implementation planning.

• Environmental and Social impacts (TBL)

• Life cycle cost consideration

• Water Quality constraints can affect the prioritization of

the selected GI technologies



Learning Objectives Revisited

• Recognize function, types, challenges

and opportunities of Green

Infrastructure technologies in urban

area

• Recognize factors affecting the

selection of GI technologies to meet

planning objectives

• Identify datasets required for planning a

successful GI implementation program

• Understand the role of hydrology and

hydraulics modeling in assessing the

various benefits of GI



Q&A

Hazem Gheith, Ph. D., PE

614.888.4953 (office)

[email protected]

planning green infrastructure implementation · planning green infrastructure implementation...

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