Successful Green Infrastructure Planning: A Micro … · 3 Imagine the result Successful Green...

Successful Green Infrastructure Planning: A Micro-Scale Modeling and Field Investigation Approach

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Hazem Gheith and Vinnie Treatment, Water Division, ARCADIS-US

Hunter Kelly, Department of Sewage and Drainage , City of Columbus

OWEA Conference 2013

2 Imagine the result

Successful Green Infrastructure Planning: A Micro-Scale Modeling and Field Investigation Approach – June 20, 2013

Topics

• City of Columbus Integrated Plan

• IP Pilot Area: Upper Olentangy basin

• Grey Solution

• Green Solution

• Green Infrastructures SWMM Modeling

• Results and Recommendations



Topics



• Grey Solution

• Green Solution





City of Columbus Integrated Plan

SSCM 2012

Model

Update

Pilot Areas

and Early

Action

Projects

Local

Models

System

Wide

Model

Affordability

Analysis

Stormwater

Strategic

Plan and

WQ

Analysis

Public

Outreach

Satellite

Communities

Integrated

Plan

IP Steering

Committee



Integrated Plan Modeling Approach

RDII

Reduction

Plan

Additional

flow between

Systems

Construct

Storm

Model

Calibrate

H/H Model

Investigate

Surface

Runoff

Define Base

Hydraulic

Deficiencies

Storm

Reduction

Plan

GI Technologies

Impact on

Stormwater

Deficiencies

Construct

Sanitary

Model

Calibrate

H/H Model

Investigate

RDII

Sources

RDII

Reduction Technologies

Impact on

SSOs and

WIBs

Sanitary Model RDII Planning Storm Model GI Planning

Base Flow

Condition

Define Base

Hydraulic

Deficiencies

Alternatives Plan Evaluation

GREY Hybrid IP

Alternative GREEN

Cost Benefit Analysis



City of Columbus WWMP Status

• Two Consent orders

• 2002: Remediation to SSOs

• 2004: Remediation to CSOs

• WWMP 2005

• 40 years schedule

• Three Tunnels

• Local storages

• Storm redirection projects

• OEPA approved WWMP in 2009

• 2012: OEPA approved to delay

ART and ORT. An integrated Plan

is due in September 2015.



Topics



• Grey Solution

• Green Solution





Pilot Area: Upper Olentangy Basin: WWMP Solution

• OSIS has seven CSO regulators

within the Upper Olentangy Basin

• Five regulators are active in typical

year storms

• City of Columbus was planning to

implemented the WWMP solutions:

• Four local storage tanks at

Frambes, Indianola, King and

Third Regulators

• Inflow redirection at First Ave

regulator (started)

OSIS



Pilot Area: Upper Olentangy Basin Enhanced Grey Solution

• Alternative 1:

• Storages at Indianola and King Regulators

• Increase capture pipe at Frambes and Third Regulators

• Alternative 2:

• One Storage at Indianola Regulator

• Increase capture pipe at Frambes and Third Regulators

• Raise weir at King Regulator



• Successful GI program should: • Capture 65 MGD of runoff (TY storms)

• Has low cost to offset the cost of the

local storages

• Six basins totaling 830 acres of surface

runoff (16-293 acres)

• CSO activations are due to: • Excessive runoff from the six basins

• Limited capture pipe capacity

• High water levels in OSIS (limiting flow

discharge from the basins)

• OSIS backing up into CSO regulators

Pilot Area: Upper Olentangy Basin Green Infrastructure Solution



GI Challenges

• Unique challenges in the study area:

• Limited open spaces

• Small-scale GI units

• Existing utility conflicts

• Disturbance to old trees

• Portion of the area is within The OSU



Where and what GI Technology?

• Peak flow should be captured or attenuated before it discharges

into the storm inlets

• Constraints

• Flow levels (low and high)

• Availability of suitable sites

• Detailed site evaluation and high resolution hydrology model

were both the key for the proposed GI program

65 MGD runoff

reduction is needed to

eliminate TY CSOs

Site Availability

Constraints

Peak Flow

Contribution at inlet

catchments



Peak Flow Constraints

• Inlet catchments Peak Flows

• Typical year storms

• 50% of the catchments receive a

maximum of 0.5 MGD. GI units could

be oversized

• GI placed in large runoff catchments

may be filled at early stage of storms

impeding their impact to attenuate

peak flows



• Identify contiguous clusters

of high peak flow catchments

• Ease planning the CIPs

• Allow interaction (hydraulic

connectivity) between the GI

units to maximize benefits

Peak Flow Constraints



Site Constraints: Rain Gardens

• Needs long streets to allow

for a train of RG units to have

measurable impact on large

peak flows

• Should be placed at

distances to avoid

disturbance to pedestrian



Site Constraints: Porous Curbs and Gutters (PCG)

• Streets with shallow slope

topology to maximize storage

• Good sites are assumed to

have 1% or less street slopes

• PCG units are assumed to

have 3.5-ft width, extended

along both sides of the street



Site Constraints: Sidewalks

• If applicable, PCG are

extended to include

sidewalks

• Only if sidewalk is within 1-

ft from the curb

• Avoid disturbance to old

trees



Site Constraints: Subsurface Detentions (SSD)

• SSD is assumed to be placed at

the downstream end of alleys,

prior to intersection with a street

• SSD was limited to low traffic

alleys that sloped down to a

street

• The alley must not contain a

sewer close to the SSD location



Site Constraints: Alley Detentions (AD)

• Alley detentions are

assumed to replace both

sides of alley edges with a

porous material overlaying a

2-ft gravel layer

• Constraints:

• Requires low slope topology

• Low traffic

• Most of the Alleys meet the

criteria



Site Constraints: Permeable Alleys

• Alley should not contain sewers

• Low surface slope to increase

storage and infiltration efficiency

• Limited application because most

alleys contain a sewer



Site Constraints: Permeable Streets

• Assumed to be used only in the

on-street parking lanes

• Low traffic

• Street should not contain

sewers

• Low surface slope to increase

efficiency



Inlet Catchment GI Application List



Topics


• Pilot Area: Upper Olentangy basin

• Grey Solution

• Green Solution





Surface Runoff Challenges

• Runoff surfaces

• Roofs

• draining to street

• Splashing over lawn

• Connected to sewer

• Commercial

• Lawn

• Alleys

• Side walks

• Parking lots

• Street and drive ways

• Traditional Catchment

Delineation Levels

• Manhole level

• Storm Inlet level



Runoff Input Parameters

• Area

• % Impervious

• Width

• Slope

• Manning

• Depression

Storage

• Infiltration

Limitations in Traditional Runoff Catchment Delineation

Some Challenges

• One slope value for all

features within the

catchment

• One sheet flow width value

for all features

• One abstraction value for

all impervious surfaces

• Etc.

Impervious Pervious

Receiving Manhole



Enhanced SWMM Modeling Resolution

Lawns

Driveways

/ Streets

House

Roofs

(discon.)

Combined

Manhole

Storm

Inlet

House

Roofs

(to street)

Commerc

ial Roof Parking

House

Roofs

(connect.)

Outfall

Alleys

Split the catchment into subareas

representing the true runoff configuration

• House Roofs

• Discharging to curb lines

• Discharging onto lawns

• Directly connected to sewers

• Lawns discharging to streets

• Alleys discharging to streets

• Commercial roofs discharging to

parking lots

• Parking Lots discharging to collectors

• Drive ways and street discharging to

storm inlets



Enhanced Delineation Improves Calibration

• Several parameters are known (roofs slope, roofs flow length, roofs

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

• Faster calibration since most parameters are known

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)



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

Enhanced Model Traditional Model



Subareas Flow Volume Contribution

• 587 storm inlet catchments in Upper Olentangy Basin

• Streets and Alleys contribute 50% of the total runoff volume

Surface Type

Runoff

Area

(AC)

Runoff Volume

June 6, 1981 (MG)

% of Total

Runoff

Volume

Roof Connected 32.00 1.58 6.1%

Roof Disconnected 101.34 5.01 19.4%

Roof Drain to Streets 15.36 0.76 2.9%

Roof Commercial 29.01 1.41 5.4%

Lawns 296.60 2.48 9.6%

Parking Lots 34.52 1.52 5.9%

Alley 116.52 5.32 20.6%

Street 165.71 7.81 30.2%

Total 791.06 25.88 100%



Topics


• Pilot Area: Upper Olentangy basin

• Grey Solution

• Green Solution





Rainfall Receiving

Waters Collection

System Urbanized land

GI Program for Upper Olentangy Basin

Goal 1:

Optimize GI units:

• Maximize inflows

• Maximize attenuation

• Minimize size

• Optimize placement to

maximize benefit

Goal 2:

Achieve WWF control at

key points in the collection

system (CSO activation)

Infiltration

Rain

Gardens

Porous Curbs

& Gutters

Porous

Sidewalks



Dynamic Routing Solution using SWMM

Lawns

Drive

Ways /

Streets

House

Roofs

(discon.)

Combined

Manhole

Storm

Inlet

House

Roofs

(to street)

Commerc

ial roof Parking

House

Roofs

(connect.)

Outfall

Alleys

P

C

G

RG

• Rain Gardens:

• 3.5 ft x 10 ft every 50 ft

• Porous Curb and Gutters

• 3.5-ft width, extended along

both sides of the street

• If applicable, PCG were extended

to include sidewalks

• Only if sidewalk is within 1-ft

from the curb



Split

Henry St. Regulator

Third Ave Regulator

Complementary Grey Solution for Upper Olentangy Basin

• Raise weir at King

Ave Regulator

• Permanently block

the diversion

between Third/Henry

Regulator Basins

• Impact on WIBs was

studied up to 10-yr

LOS storm

• No potential for new

WIBs

• Conclusion was to

block the 18”

connection pipe



Grey versus Green/Grey Infrastructure Cost 30-Year NPV Life Cycle

Cost Category Gray Alternative

(2 local storage facilities)

Medium Range Cost

Green Alternative

(RGs, PCG, PSW)

Medium Cost Range

Capital Cost $35M $57.1M

Ongoing O&M $9M $7.5M

Residue Value &

Social and

Environmental

Benefits

($13M) ($36.8M)

Total

Cost/Benefit $31M $27.8M



Conclusion • A green infrastructure program in the Upper

Olentangy basins with minimal grey

improvements could offset the need of local

storage facilities

• An educated approach utilizing GIS tools

windshield surveys helped optimizing site

selection for the different GI units

• A higher resolution modeling approach is critical

in understanding the dynamic performance and

sizing GI units

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