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
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. 2 June 13, 2008
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. 3 June 13, 2008
Improper Storm Water Connections to Sanitary Allowable in Halton until approx. 1978 Inflow : rapid storm water Infiltration : slower, seepage surges into the sanitary sewer of groundwater/storm water •Downspouts/Roof leaders into sanitary sewer •Yard drains/catchbasins •cracks or bad joints in laterals and sewers •Foundation drains/Weeping tiles •Leaking maintenance holes •Holes in Manhole Covers Reference: The City of Regina 4 June 13, 2008
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. 5 June 13, 2008
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. 6 June 13, 2008
2007 Pilot Program • Implemented between summer and winter 2007. • Participation by 27 homes impacted by multiple flooding occurrences 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) 7 June 13, 2008
Proper Collection of Sanitary & Storm Flows 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 Reference: The City of Regina 8 June 13, 2008
2007 Pilot Program Backwater Valve and Alarm Open Flap To Sewer Main Closed Flap – Protecting the Basement To 9 June 13, 2008
2007 Pilot Program Sump Pump System 10 June 13, 2008
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. 11 June 13, 2008
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. 12 June 13, 2008
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. 13 June 13, 2008
Proposed Homeowner Subsidies • Weeping Tile Disconnection/Sump Pump System: ½ of 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. 14 June 13, 2008
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. 15 June 13, 2008
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. 16 June 13, 2008
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. 17 June 13, 2008
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. 18 June 13, 2008
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. 19 June 13, 2008
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. 20 June 13, 2008
Questions 21 June 13, 2008
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