THE REGIONAL MUNICIPALITY OF HALTON Report To: From: Chair and Members of the Planning and Public Works Committee Peter M. Crockett, P. Eng., Commissioner of Planning and Public Works Date: May 16, 2007 Report No. - Re: PPW85-07 - Update on Response to Basement Flooding from High Rainfall Events and Proposed Residential Storm Water Disconnection and Inflow/Infiltration Monitoring Pilot Program RECOMMENDATION 1. THAT Council authorize staff to investigate, develop, and recommend cost sharing policy options for inflow and infiltration remediation as outlined in Report No. PPW85-07 re: Update on Response to Basement Flooding from High Rainfall Events and Proposed Residential Storm Water Disconnection and Inflow/Infiltration Monitoring Pilot Program. 2. THAT a Residential Storm Water Disconnection and Inflow/Infiltration Monitoring Pilot Program be undertaken by staff as outlined in Report No. PPW85-07. 3. THAT the following new capital project be approved: S2525A Residential Storm Water Disconnection and Inflow/Infiltration Monitoring Pilot Program with a budget of $644,400, to be financed by a transfer from the Wastewater Capital General Reserve 505320. 4. THAT the Regional Clerk forward a copy of Report No. PPW85-07 to the Towns of Halton Hills, Milton, Oakville and the City of Burlington for their information. REPORT The purpose of this report is to provide Council with an update on staff investigations of basement flooding events related to sanitary sewer backups from three intense rainfall events that occurred on July 28, 2006, December 2, 2006, and March 26, 2007, and to provide recommendations on developing, initiating and implementing action plans regarding recent basement flooding occurrences. Background Changing weather patterns over the last several years appear to be having a global impact ranging from increased hurricane and tornado frequency to increased high intensity rain and snowfall events. Environmental and Public Works professionals have initiated discussions on how climate change impacts may need to be considered in terms of infrastructure design, operations, 1
maintenance and renewal. However, in the meantime, municipalities have to ensure that the existing infrastructure can continue to provide an adequate level of service to the community. Over the last year Halton Region, along with other Southwestern Ontario municipalities, have experienced an abnormal frequency of very intense rainfall events mirroring storm events that on a probability basis should occur once in every 25 to 50 years. Over the last nine months, Halton experienced three such significant events. These storm events led to a significant number of basements being flooded across Halton Region. An investigation of each basement flooding was undertaken by Regional staff. In some instances where stormwater site drainage issues were identified, local municipal staff also investigated. This evaluation identified that there were a significant number of homes across Halton that experienced basement flooding as a result of sanitary sewer backups during each intense rainfall event. Reviewing the local environmental conditions at the time of each storm along with each respective storm pattern is essential in understanding why these specific storm events resulted in basement flooding occurrences. Sanitary sewers convey wastewater from residents, businesses and industry for treatment at a wastewater treatment plant and storm sewers convey rainwater to creeks, rivers and lakes. Sanitary sewers are also designed with an allowance for some infiltration and inflow (I/I) of storm water and groundwater in accordance with accepted design practices that will inevitably enter into the sanitary sewer. Basement flooding can occur when the amount of storm water I/I overwhelms the hydraulic capacity of the sanitary sewer system and surcharges the collection system above what can be contained within the pipe to levels that are above basement elevations. The result is the backup of sanitary sewers from floor drains or toilets/sinks into individual basements. Storm water inflows are a fast, rapid surge of water into the sanitary system from direct storm water connections such as eaves troughs, yard drains, catch basins, sump pumps, foundation weeping tiles, to name a few. Infiltration is generally a slower process whereby rainwater or groundwater seeps through the ground and then enters the sanitary sewer through joints or cracks in the sewer mains, manholes or lateral connections from homes. As the system ages, deterioration of the various components can lead to increased infiltration. In circumstances where the ground is already saturated, ground conditions may lead to a continuous flow of extraneous water into the sanitary sewer system. Typically basement flooding occurs at the lower reaches of the sewer drainage area as the I/I contributions from each property accumulate from the top end of the drainage area to the bottom. Properties unaffected by basement flooding in the higher reaches of the drainage shed contribute to basement flooding of properties in the lower reaches of the same drainage area as the extra flow makes its way down through the system. Excessive storm water I/I can also lead to other problems in the wastewater conveyance and treatment system. Too much storm water can overwhelm wastewater pumping station and treatment plant capacities. When this occurs untreated or partially treated wastewater bypasses treatment and can adversely impact the environment. Although wastewater treatment plants are designed and constructed to accommodate typical wet weather peak flows reduction of excessive I/I through storm water disconnections can free up capacity, result in higher treatment plant efficiencies and reduce treatment costs. 2
In Halton Region storm water drainage issues are within the purview of the local municipality while sanitary sewers and the treatment of wastewater is the responsibility of the Region. Accordingly, as storm water and sanitary sewer backup issues are linked it is imperative that solutions look at a combined resolution of the problem between Halton Region, its local municipal counterparts and the individual homeowners when developing policies to address basement flooding issues. Examples of factors that contribute to excessive inflow and infiltration entering sanitary sewers which may exacerbate or result in basement flooding occurrences include: Storm water inflow from direct connections of roof leaders, foundation weeping tiles, sump pumps etc. to the sanitary sewer system. Although such connections to the sanitary sewer are currently prohibited by the Building Code, prior to 1968 and possibly later, these connections were permitted, and consequently still exist, in much of the mature areas in Halton Region. These connections are a major cause of excessive storm water inflows into the sanitary sewer system; Site grading changes that have occurred as part of landscaping improvements over time can also increase flow to the sanitary sewer from foundation drains; Groundwater and/or storm water entering the sanitary sewer through cracks and joint leaks in wastewater laterals and sewer mains which can occur as the system ages or as the result of ground settling or tree root intrusions. Other inappropriate direct storm water connections to the sanitary system. Areas in Halton Region that have experienced sanitary sewer backups due to storm water impacts are typically in older drainage areas where direct storm water connections to sanitary sewers exist. The Three Rainfall Events July 2006 In July, two high intensity storms moved through Halton within hours of each other. The ground was fully saturated from the first storm when the second storm front moved through the area. As the ground had limited ability to absorb additional storm water this created a situation where both inflow and infiltration were a factor in surcharging the sanitary wastewater system creating basement flooding from both overland sources as well as sewer backups in localized areas of Burlington. Halton Region was notified and recorded 65 basement flooding occurrences from sanitary sewer backup from this July storm event. December 2006 The December storm was a highly intensive rainfall event with quantities and duration representing a nearly 1 in 50 year storm event based on data captured from rain gauges. This storm was a less localized storm than the July event and triggered inflow and infiltration as well as surface run off problems in Oakville, Burlington, Milton, and Georgetown, with some homes in Oakville and Burlington being impacted by basement flooding for a second time. Halton Region was notified and recorded 37 confirmed basement flooding occurrences from sanitary sewer backup from this December storm event. 3
March 2007 The March event was a sequential storm event, similar to the July 2006 event, where one storm system moved through Halton, followed shortly by a second wave of intense storms. However the March event also had ground conditions that further exacerbated by the existence of spring frost melt and partially frozen ground which contributed heavily to the saturated ground conditions prior to the second storm cell moving through. This created very high surface water runoff as well as high inflow and infiltration contributing to the surcharging of sewer mains in various areas across Burlington and Oakville resulting in pockets of basement flooding and some homes being impacted for a third time since July 2006. Halton Region was notified and recorded 44 confirmed basement flooding occurrences from sanitary sewer backup from this March storm event. Discussion These three rainfall events are not dissimilar to the May 12-13, 2000 storm, which was identified as having an intensity of between a 25 and 50 year rainfall event and resulted in the flooding of local rivers, streams, and drainage systems. This storm resulted in approximately 180 basement flooding calls across Burlington and Oakville. Similar to many storm events, these events were localized in nature, and did not necessarily impact all areas of the Region. These three most recent high intensity rainfall events resulted in basement flooding occurrences reported to Halton Region from sanitary sewer backups totalling 146 occurrences (128 in Burlington and 18 in Oakville) with some individual homes being flooded up to three times during these three specific events. In all situations, staff responded as rapidly as possible as per the appropriate Regional Policies and Procedures to meet with the homeowners on site to conduct an initial assessment. If it was confirmed that the flooding was as a result of a sanitary sewer backup staff would then distribute an Ex-gratia grant form to the impacted resident as per Halton Region policy. The Ex-gratia grant provides any Halton homeowner impacted by basement flooding due to sewer backup with a one time payment of $500 on a without prejudice basis and does not require that the homeowner waive any of their existing legal rights. This immediate review generally indicates whether the flooding is a result of storm water entering the home as a result of surface drainage (e.g. entering through doors, windows, etc.) which is within the purview of the local municipality or as result of sanitary sewer backup which would be investigated by Regional staff. The initial assessment ensures that the calls are being directed to the proper muncipal authority. Through staff s ongoing investigation it was determined that Halton Region s sewer design standards, maintenance practices, and infrastructure condition were not a contributing factor to these recent basement flooding occurrences. Many of the affected drainage areas and sewers were designed and constructed prior to the creation of the Region in 1974. At that time, direct connection of roof leaders and foundation drains was the norm. As a result, staff has concluded that storm water inflow through direct connections (e.g. weeping tiles and downspout connections) from the private property side and increased levels of infiltration resulting from saturated ground conditions resulted in excessive extraneous flows to the sanitary system. The result was surcharging of both mains and laterals which in turn lead to the sanitary backups. As the combination of the contributing inflow factors varies from house to house and between drainage 4
areas, each situation needs to be reviewed on a case by case basis to find the correct solution to remediate each individual problem. It should be noted that Halton Region is not alone in experiencing this situation. During this year s National Water and Wastewater Benchmarking event attended by representatives of Halton Rgion, specific workshops were organized to discuss inflow and infiltration issues with municipalities from all across Canada. Key findings as presented at the benchmarking event indicate that that relationship between rainfall dependent I/I rates and infrastructure age is significant with flows increasing exponentially as the infrastructure ages from an estimated 12,500 L/ha/d at age 0 to between 40,000-63,000 L/ha/d at age 50, and in addition I/I contributions from laterals can be as high as 70% but on average contribute 50-60% of total I/I response in the system. Approximately 35% (577,980 metres of 1,635,712 metres) of Halton Region s linear wastewater infrastructure is approaching the 50 year mark (being constructed prior to 1960). This would indicate that in all likelihood, the properties connected to these mains also have storm water connections to the sanitary system as this was permitted in the Ontario Building code until approximately 1968. This correlation would indicate that the likelihood of increased impacts to the sanitary sewer system will continue to increase as the system continues to age unless measures are taken to limit excessive I/I from entering the sanitary sewer system. Fortunately as a result of Building Code revisions and municipal bylaws newer residential areas are rarely impacted by sanitary sewer surcharging as storm water connections to the sanitary sewers are prohibited. Staff from numerous Ontario municipalities, along with the National Water and Wastewater Benchmarking Association, and other organizations are initiating discussion to deal with increased flooding and changing weather patterns, the associated impact on water and wastewater infrastructure and potentially on design standards. In addition, the National Water and Wastewater Benchmarking Association is currently in the process of initiating a comprehensive survey with respect to Inflow and Infiltration, remediation approaches and cost sharing initiatives to gather as much data as possible to allow members, including Halton Region, to leverage experiences, strategies and successes. Typical remediation measures focus on disconnection of any direct connections of foundation drains, downspouts and area lot drains from the sanitary sewer system on each individual property and the installation of the backflow prevention valves. A sump is constructed in the basement with discharge to the surface designed to flow away from the residence or building. Lateral lining is also effective in addressing infiltration issues from leaking or compromised laterals. The backflow prevention valve closes automatically when the sanitary main surcharges thereby preventing flow from backing up from the sanitary main into the individual basement. When the backflow prevention valve has been activated water usage in the residence must be limited to ensure that the individual property does not flood itself. Therefore it is critical that all direct connections to the sanitary sewer on the private side of the backflow prevention valve are removed in order for the property not to flood itself from storm water. 5
Staff have started gathering information on what Halton s local comparators are doing in this area currently in order to provide a picture of what s going on in the industry pertaining to policies and subsidy programs. Basement Flooding Programs Halton Region s current Wastewater System By-law 184-95 provides the authority to order the disconnection of an improper hook-up, such as a direct connection of a roof leader or foundation drain to the sanitary sewer with 60 days notice. However, the cost to the homeowner can be quite significant and to date Halton Region has not compelled homeowners to disconnect under the Bylaw. In other municipalities subsidy based programs have been adopted to help offset the cost to the homeowners as noted below: Peel Region - Basement Flooding Protection Subsidy: Included is a subsidy of $2,750 for the installation of a sump pump and a backflow valve conditional on an indemnity waiver. City of Toronto Basement Flooding Protection Subsidy: Included is a subsidy of up to $1,500 for sump pump installation, up to $1,000 for backwater valve installation, or up to $2,300 for a combination of sump pump and backwater valve and up to $500 for downspout disconnection. Homeowners that apply must have documented basement flooding history. After a spate of flooding in August 2005, the City of Toronto set aside a $4 million fund to help homeowners with vulnerable basements take preventative measures. City of St. Catharines Flood Alleviation Program: The City provides grants of up to $3000 to homeowners who have documented recurring sanitary back-ups as a result of sewer surcharging. This grant is to offset the cost of eligible works including backwater valve installation, sump pump installation with battery back-up, the disconnection of weeping tiles from the sanitary sewer, the reconnection of these weeping tiles to the sump pump, all materials, labour and restoration. City of London- Sump Pump Subsidy Program: The City subsidizes the program with $1000 for a sump pump installed inside the basement and $1,300 if connection with the weeping tile is outside. The City also provides a subsidy of $250 for backflow valve installations. Generally, municipalities have taken the approach of subsidizing at various levels of private side disconnection work and installation of backflow prevention valves. However, we are aware that other municipalities have funded or are considering funding the total cost of private side storm water disconnection measures in areas that have been severely impacted. Notwithstanding the customer service, investigative, and analytical actions taken to date, staff believe more needs to be done to assist residents in resolving and preventing these highly unpleasant situations and that some high priority remediation efforts are called for. Work in Progress Subsequent to the July 2006 rainfall event which impacted many Burlington residents, technical staff initiated a comprehensive review of the potential causes of the flooding to assess opportunities to take remedial action. As noted earlier there are many possible contributing factors that have to be reviewed to determine an appropriate course of action. In the fall of 2006, 6
staff retained Stantec Consulting at a cost of approximately $80,000 to undertake six months of flow monitoring to assess areas that had experienced basement flooding, and assist staff in conducting household drainage surveys. These household drainage surveys include for each residence a review of lot grading, lateral inspections, roof leader and weeping tile connection assessments, and a determination as to whether homes have backflow prevention devices in place and sump pumps installed. Twenty three of the 65 impacted homes from the July event agreed to participate in the household drainage surveys. In addition, staff have updated the Closed Circuit Television (CCTV) inspections for all the mains in the area to confirm their condition and whether the condition was a contributing factor to the surcharging. No blockages were found through this inspection program, but some isolated cracks were identified on a few mains that could contribute to infiltration during high intensity rainfall events. These cracks are typically seen in aging infrastructure and do not necessarily require further remedial action, however, they do increase the amount of infiltration that can enter the wastewater system during rainfall events. Staff intends to continue to monitor the system to identify areas that require sewer rehabilitation or lining to address severe infiltration issues. Halton Regional staff have also intensified normal preventative inspection and maintenance activities such as improving manhole benching and increasing flushing programs throughout impacted areas. Staff have also produced and distributed information pamphlets to the impacted homeowners that provide tips and suggestions for what individual homeowners can do to with their infrastructure to minimize basement flooding occurrences. Similar information is also available on Halton s website. Due to the significant impact to the homes in Ward 3 of the City of Burlington as a result of the July 2006 storm event, at the Councillor s request, staff convened a Public Information Centre that was held in January 2007. At the information centre staff apprised Burlington Ward 3 residents of information related to the basement flooding and causes such as excessive inflow and infiltration, findings to date, and next steps, including what the residents can do to help their own situation. The findings to date from the investigation also indicate that any solution is not a one size fits all, but requires a case by case review of each individual property to determine the condition of the lateral, whether or not weepers and downspouts have been disconnected, lot drainage composition, and confirm the presence of a sump pump and its discharge point. As a result of the two storms subsequent to the July storm, staff investigative work has expanded to include various other clusters of impacted homes on a priority basis based on flooding frequency throughout Halton Region. Investigative work has commenced with household drainage surveys, and CCTV inspections. In addition, staff is also in the process of conducting hydraulic modelling exercises to review and confirm system capacity. Next Steps Due to the sensitivity and urgency of this issue staff have developed and is recommending an approach that includes a combination of near term to long term mitigation plans. Unfortunately, based on the storm events of the last 8 months it is reasonable and highly likely that storms of the magnitude that would cause basement flooding can be expected to occur in the future. It is impossible to predict the exact timing of when and where such a storm would occur and hence near term plans will begin to address problem areas expeditiously. 7
As many homes across the Region have been affected since 2000 it will not be possible to address all areas simultaneously. Therefore it is recommended that these plans be implemented based on priority determined by number of reoccurring basement flooding incidents that have affected each homeowner and progress of household drainage survey investigations to determine and define appropriate options for problem resolution. Near term solutions will enable staff to expeditiously implement solutions that address those homes that have been flooded multiple times. Longer term solutions will include development of options for affected homeowners that provide relief financially through potential cost sharing programs as well as provide relief to the wastewater system by reducing or eliminating the extraneous flows from the storm water inflow connections to the sanitary sewer system. Residential Storm Water Disconnection & Inflow/Infiltration Monitoring Pilot Program Longer term solutions will require a better understanding of actual costs and effectiveness of various mitigation measures to ensure that funds are spent on those measures that achieve the best results. It is critical to determine the most technically and cost effective options as the cost of the disconnection alternatives can be significant. Also, information is required on the typical construction situations that can be expected and the impact of these variations on installation or cost should be studied for designing the overall long term strategy and implementation/cost sharing policies to be applied in collaboration with local municipalities and homeowners in affected areas across the Region. To better design an appropriate strategy that is fiscally responsible and effective, staff is recommending that Council authorize the initiation of a residential storm water disconnection and monitoring pilot program. The pilot program will allow Halton to expeditiously address homes that have been most impacted by multiple basement flooding occurrences since July of 2006 while gathering critical information required to develop a more comprehensive strategy to addressing basement flooding across the Region. This pilot program will include for each residence: the disconnection of roof leaders and weeping tiles from the sanitary system; lining of the wastewater laterals if required; the construction of sumps to collect foundation drainage and installation of sump pumps with appropriate discharge and drainage away from the house; and the installation of a backflow prevention valve (the backflow prevention valve may be installed within the homeowner s basement or outside of their home in a maintenance hole on either private property or within the public right of way in consideration of cost, technical feasibility and effectiveness as determined by staff with the consent of the homeowner) These measures should help prevent similar basement flooding occurrences for these homes in the future as a result of a surcharged sanitary sewer system during high rainfall events. This work is proposed to be undertaken by a private contractor with all costs to be paid by Halton Region. 8
Construction and installation of the remediation measures will be initiated as soon as possible after Council approval. The following eligibility criteria will be used to determine which homes will be included within the pilot program: Program eligibility criteria: That the property has been flooded as a result of sanitary sewer backup two or more times since July 1, 2006. That staff determine the actual cause of each flooding event was a sanitary sewer backup either through a visual inspection of the property; or the submission of appropriate documented evidence from the homeowner (such as an insurance claim filing); or a flooding incident reported to and on file with Halton Region; and that each sanitary sewer backup occurred as a result of a rainfall event and not as a result of a blocked or compromised lateral connection. All required pilot program documentation including any necessary releases, notifications and/or indemnities related to the Region s contractors undertaking the work have been authorized by the homeowner. In consideration that each installation situation may be different, the degree of which is not yet clearly understood, and that costs may vary significantly, it is proposed that the Commissioner of Planning and Public Works retain the right at his sole discretion to ultimately approve each homeowner s eligibility in the pilot program to ensure that Halton s fiscal interests are respected. Although complete storm water disconnection from the sanitary sewer system of individual homes eligible to participate in the pilot program will provide valuable information on the variety of construction situations that may be encountered throughout the Region it will also be critical to confirm the effectiveness of various remedial measures in mitigating inflow and infiltration levels. Staff have identified a small residential street in the City of Burlington that includes homes that have been flooded during each of the three recent significant rainstorms identified in this report and therefore meet the proposed pilot program eligibility criteria. This area provides a unique opportunity through the pilot program to study and monitor the effectiveness of various storm water disconnection measures. It is a short street with only eight homes with no upstream contributions to the wastewater main. In addition, several of these homes participated in the household drainage surveys and staff are aware of the current situation with respect to the existence of storm water connections from the private property side to the sanitary sewer system. Staff are proposing to include all eight homes on this street, although not all homes on this street experienced the same level of basement flooding, in the pilot disconnection program to allow flow monitoring data to be collected and analysed for the whole street. Also as part of the pilot storm disconnection monitoring program flow meters and data loggers will be installed within system and the individual homes to enable the collection of relevant data that will allow staff to assess the volume of inflow that has been mitigated as a result of these disconnections. The data will permit staff to extrapolate the overall contribution of inflow to other surcharging/flooding situations throughout the Region and assess actual costs to undertake each remediation measure. This data 9
will also be used to understand the impact of remediation on Halton s wastewater treatment facilities and conveyance systems including the Regions wastewater pumping stations. Once this work has been completed and adequate data has been collected staff will analyse the results, determine the effectiveness of the various approaches and recommend the most effective solutions both from a cost and technical point of view. It is anticipated that, based on the information gathered by staff to date, the pilot program may involve approximately 20 homes in the Town of Oakville and the City of Burlington including the eight homes on the small residential street referenced above. Although a key objective of the pilot program is to determine actual costs to undertake these measures, staff estimate that, based on current best estimates, the total cost of proposed pilot program will amount to approximately $644,400 (see Attachment #1). Should the program costs increase beyond our current estimates staff will report back to seek further authority and direction on the pilot program. Based on the results of the pilot program staff will also recommend options for Council s consideration upon completion of and analysis of the program and development of an appropriate remediation plan for affected areas across the Region. It is anticipated that pilot program construction will occur during the summer of 2007 and data will be gathered during the fall of 2007 with program recommendations developed for Council consideration by the late 2007 or early 2008. Remediation Subsidy Policy Development As noted above, other municipalities have embarked on various types of subsidy programs to address I/I issues. Staff is in the process of continuing to collect this data and reviewing what other municipalities are doing in terms of policy development for addressing basement flooding. Using the data derived from the pilot project, staff will work with the affected local municipalities to develop a strategy for further expansion of the remediation program into other affected drainage areas throughout the Region based on the development of a reasonable three-way cost sharing approach involving the Region, the local municipality and the homeowner. Staff have been meeting regularly with the City of Burlington staff to jointly discuss the three most recent high intensity storm events and opportunities to collaborate to successfully resolve this issue for their community. Burlington staff have indicated that resolution of this issue is a high priority for them as well, and staff is committed to working together to find and recommend solutions for our respective Council s consideration. Halton Regional staff will also be continuing discussions with Town of Oakville staff to investigate their level of interest in developing a common policy approach to assist the homeowners affected by the recent storms in Oakville and will continue those discussions with the other affected local municipalities as appropriate. 10
Long Term Considerations Staff will continue to investigate all the various contributing factors, assess the results from the National Water and Wastewater Benchmarking Association survey initiative, and discuss with other engineering professionals the impact of global climate change on infrastructure in order to effectively explore and develop options to alleviate future basement flooding occurrences. Some longer term more comprehensive programs may include: lateral and manhole lining programs, changes to design standards, construction of retention systems or hydraulic realignment of mains and discharge points. Provision of additional conveyance capacity may also be considered where appropriate. Over the long-term the program objective will be to continue to prevent storm water and excess infiltration from entering the wastewater conveyance and treatment system through the application of the subsidy program under development and potential structural alternatives as noted above. FINANCIAL/PROGRAM IMPLICATIONS Due to the significant ongoing investigative work being undertaken by staff and consultants to understand the inflow and infiltration issues in the impacted areas, existing operational budgets are unable to absorb any further incremental costs associated with the pilot program without severely impacting the operating budget. Therefore, staff recommends that a new capital project be approved as follows: S2525A - Residential Storm Water Disconnection and Inflow/Infiltration Monitoring Pilot Program with a budget of $644,400, to be financed by a transfer from the Wastewater Capital General Reserve 505320. This total capital funding allocation of $644,400 will allow staff to undertake the pilot program, gather critical data and information in order to develop a comprehensive long term basement flooding mitigation strategy. Upon completion of the pilot program staff will report back on the financial implications of the long term mitigation strategy and any associated policy recommendations. RELATIONSHIP TO THE STRATEGIC PLAN This is operational issue with no direct relationship to the 2007 Planning & Public Works Committee Plan. Conclusion Basement flooding resulting from a sanitary sewer backup is a complex and serious issue that is not unique to Halton and is extremely disruptive and upsetting for affected residents. The pilot program will focus on homes that have been impacted multiple times being considered a high priority for remediation work. 11
A combination of the pilot program, a possible remediation subsidy, and longer term solutions need to be considered to mitigate the severity of and occurrence of future basement flooding. The influence of climate change on infrastructure design and management must also be carefully considered. While subsidy programs may provide some individual homeowner relief, it is possible that those properties upstream of the impacted area will have no motivation to voluntarily disconnect their roof leaders, sump pump and weeping tiles from the sanitary sewer system. Accordingly, due to the cumulative nature of drainage area impacts, the downstream homes may still experience flooding unless policies are holistic in nature and encompass entire drainage areas with mandatory disconnections. Staff will continue to investigate opportunities and mechanisms within existing polices and legislation and recommend new approaches and policies as necessary. Staff will also continue to work closely with local staff to develop a recommended approach for any potential subsidy program for residents. Any such recommendations will be brought forward for Council consideration prior to implementation. Respectfully submitted, Kiyoshi Oka P. Eng. Director, Environmental Services Peter M. Crockett P. Eng. Commissioner of Planning and Public Works Approved by J. E. MacCaskill Acting Chief Administrative Officer If you have any questions on the content of this report, please contact: K. Oka, P.Eng. Tel. # 7602 L. Petelka Tel. # 7640 12
Attachment #1 to PPW85-07 Residential Storm Water Disconnection and Inflow/Infiltration Monitoring Pilot Program Item Remedial Measure # of Households Disconnection Costs 1. Disconnect Downspouts & Weepers, Installation of Sump Pumps & Backflow Valves Cost per household Total 20 $15,000 $300,000 2. Lateral Lining (15m/household) 20 $7,500 $150,000 Evaluation 3. Data Logger (System)(6 months) $30,000 4. Small sump data loggers ( Household) (6 months) 8 $6,000 $48,000 5. Installation of Flow meters $9,000 Subtotal $537,000 Engineering @15% $80,550 Contingency @ 5% $26,850 Total $644,400 13