Completion of 2007 Residential Storm Water Disconnection and - - PowerPoint PPT Presentation

Completion of 2007 Residential Storm Water Disconnection and Inflow/Infiltration Monitoring Pilot Project and Proposed Basement Flood Prevention Subsidy Program Report PPW41-08

Presentation to Planning and Public Works Committee June 11, 2008 Kiyoshi Oka P. Eng., Director of Environmental Services

June 13, 2008

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Overview

• Causes of basement flooding (PPW85-07)
• Results of the 2007 storm water disconnection pilot project.
• Outline a proposed approach to assist affected

homeowners.

• Present a strategy to develop longer term comprehensive

solutions.

June 13, 2008

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Contributing Factors to Basement Flooding from Storms

• Excessive inflow/infiltration (I/I) entering the sanitary

sewer system.

• More severe and frequent storms

– Changing precipitation patterns, Climate Change

• Not unique to Halton.

June 13, 2008

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Improper Storm Water Connections to Sanitary

Allowable in Halton until approx. 1978

Reference: The City of Regina

Inflow: rapid storm water

surges into the sanitary sewer

• Downspouts/Roof leaders
• Yard drains/catchbasins
• Foundation drains/Weeping tiles
• Holes in Manhole Covers

Infiltration: slower, seepage

• f groundwater/storm water

into sanitary sewer

• cracks or bad joints in laterals

and sewers

• Leaking maintenance holes

June 13, 2008

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Impacts of Excessive I/I

• Sanitary sewers properly designed to convey wastewater

and some I/I.

• Too much stormwater I/I can easily overload the sewer

result in “surcharging” and wastewater backing up into basements through floor drains or fixtures.

• Cannot reasonably build a sewer system to handle

excessive I/I and protect against severe storms.

June 13, 2008

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Recent Basement Flooding Events and 2007 Pilot Program

• Three severe storm events on July 27/28 2006,

December 1, 2006 and March 26, 2007.

• Region responded to 146 basement flooding occurrences

from sanitary sewer backups.

• Older areas of Burlington and Oakville most impacted.
• Prior to 2006 Halton had not experienced such

widespread flooding since 2000.

• By adoption of Report PPW85-07 Council authorized the

initiation of a pilot storm water disconnection program:

– Immediate relief to residents most impacted to mitigate the potential for future flooding, – Gather information to design solutions.

June 13, 2008

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2007 Pilot Program

• Implemented between summer and winter 2007.
• Participation by 27 homes impacted by multiple flooding
• ccurrences since July/06.
• Region to gather valuable data for use in developing a more

comprehensive flood prevention program. Information collected included:

– Cost – Typical construction situations – Effectiveness of disconnections through flow monitoring (also through resident feedback)

June 13, 2008

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Proper Collection of Sanitary & Storm Flows

Reference: The City of Regina

Pilot program –work performed:

• Disconnection of downspouts/weeping tiles.
• Installation of sump pump, with storm water

discharging away from house as required.

• Installation of backwater valve with alarm.
• Lateral repair/replacement if required.
• Lot grading improvements if required

June 13, 2008

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2007 Pilot Program

Backwater Valve and Alarm

Closed Flap – Protecting the Basement

To Sewer Main To

Open Flap

June 13, 2008

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2007 Pilot Program

Sump Pump System

June 13, 2008

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Pilot Program – Flow Monitoring Component

• Flow data collection devices “data loggers” installed on

14 sump pumps to measure effectiveness of stormwater disconnections.

• Data being collected to quantify flows and understand

seasonal influences.

June 13, 2008

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Wastewater System By-law 184-95

• By-law allows Council to order storm water disconnections.
• Approximately 50,000 homes throughout Halton affected.
• Significant cost for resident to comply with Regional By-law.
• After evaluating the risks we do not believe that mandatory

disconnection is required at this time.

• In order to minimize future liability in light of related court

cases staff request Council to enact a Regional policy that the Region will not require mandatory disconnections under Section 21 of By-law No. 184-95.

June 13, 2008

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Proposed Flood Prevention Subsidy Program

• Removing all sources of excessive I/I from the system is not feasible

in the immediate term.

• Until longer term solutions have been developed there is a need to

provide assistance to impacted residents.

• Basement flood prevention subsidy programs are a important

customer service initiative in many municipalities (Toronto, London,

• St. Catharines and others).
• Provides financial assistance to homeowners to address improper

connections.

• Staff are recommending a new Halton basement flood prevention

subsidy program.

June 13, 2008

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Proposed Homeowner Subsidies

• Weeping Tile Disconnection/Sump Pump System: ½
• f invoiced cost to a maximum of $1800 (including

materials, labour, permit, taxes).

• Downspout Disconnection:

½ of cost up to a maximum of $250.

• Backwater Valve: ½ of invoiced cost to a maximum of

$675 (including materials, labour, permit, taxes). Storm water must also be disconnected.

June 13, 2008

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Subsidy Program – Step by Step

• Homeowner initiates contact with Region staff.
• Staff or representative assesses home to confirm work

required.

• Homeowner obtains permit for work required by the Local

Municipality.

• Homeowner arranges for work to be completed and

inspection by Local Municipality.

• Region confirms that work has been completed.
• Homeowner submits receipts, copy of permit, proof of

inspection and application/waiver form to the Region.

• Region issues subsidy payment to homeowner.

June 13, 2008

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Flood Prevention Subsidy Participation

• Ex-gratia Grants given out to 839 households who experienced

flooding over the last 10 years.

• Difficult to accurately predict actual participation rate.
• Staff anticipate a participation rate of 50 homes/year in 2008 and

150 homes/year between 2009-2011.

• 90% of available subsidies for homes that have experienced past

flooding incidents.

• Up to 10% of subsidies available for homeowners who wish to

participate but have not been impacted by flooding.

• Program costs detailed in Report No. PPW41-08.

June 13, 2008

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Flood Prevention Outreach Program

• Initiate public education and outreach to inform

homeowners about basement flood prevention and subsidy program.

• Collaborate with Local Municipalities to build broader

community awareness and provide seamless customer service to Halton residents.

• Brochures, participation in community events, media

advertising, linking of Regional/municipal websites.

June 13, 2008

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Next Steps Proposed Inflow/Infiltration Study

• Not reasonable or feasible to provide subsidies for all homes with

improper storm water connections (estimated at nearly 50,000 homes).

• I/I study proposed to be initiated in 2009 to determine the best approach

to address basement flood prevention on a drainage shed basis.

• Staff to prioritize study areas focusing on those historically susceptible to

basement flooding.

• Study to include expansion of Halton’s existing flow monitoring program.

June 13, 2008

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Proposed Inflow/Infiltration Study

• Study may take up to two years to complete in order to assess all

seasonal weather patterns.

• Possible options and alternatives that will be reviewed include:

– Lateral and manhole lining programs. – Changes to design standards. – Provision of additional capital system improvements (i.e. conveyance capacity, storage) – Continuation of subsidy/outreach program.

• Recommendations for consideration by Council following study.

June 13, 2008

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Summary

• Basement flooding is extremely disruptive for impacted residents.
• Pilot program successful in addressing homes most impacted by

recent basement flooding and gathering valuable information.

• The proposed Flood Prevention Subsidy Program provides

financial assistance to homeowners so that they may correct improper storm water connections and mitigate the potential for future flooding.

• Longer term, sustainable solutions require a more detailed

understanding of Halton’s I/I issues so that entire drainage sheds may be addressed.

June 13, 2008

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Questions