Mitigating Urban Flood Risk in New Residential … · 12.09.2016 · 3 © Amec Foster Wheeler 2016 Problems … I&I Inflow and Infiltration leading to flooding

© Amec Foster Wheeler 2016.

12 September 2016

ENVIRONMENT & INFRASTRUCTURE

Peter Nimmrichter, M.Eng., P.Eng.

Associate and Climate Change Specialist, Water Resources

Burlington, Ontario, Canada

Inflow/Infiltration and Stormwater

Mitigating Urban Flood Risk in

New Residential Subdivisions

© Amec Foster Wheeler 20162

Project Overview

The next step from the Best

Practices Guide: Management of

Inflow and Infiltration in Urban

Developments (February 2015)

Taking the next step with a focus on

I&I issues and stormwater

management issues

Capacity building towards flood

resilience in new urban residential

developments

Developing a guidance document

outlining urban flooding best

management practices for new

urban residential developments

© Amec Foster Wheeler 20163

Problems … I&I

Inflow and Infiltration

leading to flooding

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Problems … I&I

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Problems … I&I

Source: http://www.kwl.ca/sites/default/files/IandI-paper-OCR.pdf

© Amec Foster Wheeler 20166

Inflow & Infiltration Issues …The process

Design/

SpecificationConstruction Inspection

Acceptance/ Transfer

Operations / Maintenance

Full life cycle design

Specifications to ensure objectives

Use of required materials

Good construction practices

Proper training

Adequate inspection procedures

Adequate monitoring

Proper training

Contract

language

Assumed period of consideration for study

Proactive

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Inflow & Infiltration Issues …But not in New Construction

Blue text - Inflow

Red text - Infiltration

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Inflow & Infiltration Issues …We’ve always known about it

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Problems … I&I

© Amec Foster Wheeler 201610

Majority of problems experienced with private laterals originate from initial construction

Private property sources contribute ~40% of total system I&I

A significant amount of I&I from new subdivisions due to poor workmanship and

construction loads

Chimney frame leaks are one of the most significant sources of extra stormwater into

the sanitary system

I&I control in new developments is most cost effective, as deficiencies can be fixed

prior to assumption of sewers by municipalities

Enforcing and raising the construction standards including updating the Sanitary

Sewer System Inspection requirements, Testing and Acceptance Guidelines in

collaboration with municipal partners and undertaking flow monitoring in new

developments are instrumental to continued improvement

Homeowner education

Opportunities to engage homeowners when property is up for sale

Inflow & Infiltration Issues …Some current knowledge

© Amec Foster Wheeler 201611

Problems … I&I

If we don’t ask for

what we really want

we may not get it.

If we don’t check

that we’re getting

what we asked for

we may not get it.

Technologies exists

to mitigate I&I

issues … are we

using them ?

© Amec Foster Wheeler 201612

Problems … Stormwater

Storm sewer surcharging

leading to flooding

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Stormwater Issues …

© Amec Foster Wheeler 201614

Stormwater Issues …Scale – Watershed/Subdivision

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Stormwater Issues …Scale – Watershed/Subdivision

Stormwater system design / stress testing

100 year, 350 year, 500 year, Regional Storm

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Stormwater Issues …Scale – Lot Level

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Stormwater Issues …Scale – Lot Level

© Amec Foster Wheeler 201618

Rainfall is increasing …

Current: 1963 IDF Curve

2012 IDF Curve

1.0

10.0

100.0

1000.0

5 10 15 30 1 2 6 12 24

Inte

snit

y (m

m/h

r)

Duration (min/hour)

2020 or 2050 IDF Curve

Stormwater Issues …Climate Change

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Problems … Stormwater

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Inflow & Infiltration Issues …

Lisgar District Basement Water Infiltration Investigation

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Stormwater Issues …Resistance/Resilience

Permanent resistance measures designed to

stop water entering your home either through

existing openings or to stop it penetrating the

walls.

Temporary resistance measures aim to keep

floodwater out of a building by putting in place

devices that block floodwater ingress.

Resilience measures allow a building to flood but

constructing the interior from materials that are

not damaged by water.

© Amec Foster Wheeler 201622

Stormwater Issues …Resistance/Resilience

Thank you!

23 © Amec Foster Wheeler 2016

ENVIRONMENT & INFRASTRUCTURE

Peter Nimmrichter, M.Eng., P.Eng.

Associate and Climate Change Specialist, Water Resources

Burlington, Ontario, Canada

[email protected]