Mitigating Urban Flood Risk in New Residential Subdivisions

Transcription

1 Mitigating Urban Flood Risk in New Residential Subdivisions Inflow/Infiltration and Stormwater 12 September 2016 ENVIRONMENT & INFRASTRUCTURE Peter Nimmrichter, M.Eng., P.Eng. Associate and Climate Change Specialist, Water Resources Burlington, Ontario, Canada.

2 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 2

3 Problems I&I Inflow and Infiltration leading to flooding 3

4 Problems I&I 4

5 Problems I&I Source: 5

6 Inflow & Infiltration Issues The process Design/ Specification Construction Inspection Acceptance/ Transfer Operations / Maintenance Use of required materials Good construction practices Proper training Full life cycle design Specifications to ensure objectives Contract language Adequate inspection procedures Adequate monitoring Proper training Assumed period of consideration for study Proactive 6

7 Inflow & Infiltration Issues But not in New Construction Blue text - Inflow Red text - Infiltration 7

8 Inflow & Infiltration Issues We ve always known about it 8

9 Problems I&I 9

10 Inflow & Infiltration Issues Some current knowledge 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 10

11 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? 11

12 Problems Stormwater Storm sewer surcharging leading to flooding 12

13 Stormwater Issues 13

14 Stormwater Issues Scale Watershed/Subdivision 14

15 Stormwater Issues Scale Watershed/Subdivision Stormwater system design / stress testing 100 year, 350 year, 500 year, Regional Storm 15

16 Stormwater Issues Scale Lot Level 16

17 Stormwater Issues Scale Lot Level 17

18 Intesnity (mm/hr) Stormwater Issues Climate Change Rainfall is increasing 2012 IDF Curve Current: 1963 IDF Curve or 2050 IDF Curve Duration (min/hour) 18

19 Problems Stormwater 19

20 Inflow & Infiltration Issues Lisgar District Basement Water Infiltration Investigation 20

21 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. 21

22 Stormwater Issues Resistance/Resilience 22

23 Thank you! ENVIRONMENT & INFRASTRUCTURE Peter Nimmrichter, M.Eng., P.Eng. Associate and Climate Change Specialist, Water Resources Burlington, Ontario, Canada 23