Corporate Report. Report from Transportation and Environmental Services, Environmental Services

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1 Corporate Report Report from Transportation and Environmental Services, Environmental Services Date of Report: January 9, 2015 Date of Meeting: January 26, 2015 Report Number: TES File: Subject: Investigation into flooding in south-west St. Catharines Recommendation That Council receive the report from Transportation and Environmental Services, dated January 9, 2015, for information purposes. Summary This report summarizes findings from the investigation of widespread basement flooding as reported throughout south-west St. Catharines due to an intense, localized rain storm on July 27 and 28, 2014, generating up to 70 mm of rain fall in this area over 16 hours. Subsequent investigations identified multiple contributing factors to the flooding including, extraordinarily high rainfall volume and intensity, storm water infiltration, and partial sewer obstruction by foreign materials. As such intense rainfall events are becoming more frequent, an action plan prepared by staff is being implemented as resources become available to improve the performance of this sewer system through enhanced maintenance activities, capital works and regular inspections. Background Multiple properties have reported flooding in south-west St. Catharines during significant rainstorm events in the last two years with the most recent incident occurring on July 27 and 28, The July 28, 2014 storm was extremely intense, but also extremely localized to the rural area in west St. Catharines and the urban area in south-west St. Catharines. This report focuses on the urban area in south-west St. Catharines which is bounded by Twelve Mile Creek to the south, Rykert Street to the north, Louth Street to the east and First Street Louth to the west. The impact of the storm in the rural area of west St. Catharines is the subject of a separate report to Council. This report outlines the short term actions the City has completed to mitigate basement flooding in the area, as well as actions taken to investigate the cause of flooding, the findings of those investigations and outlines an action plan to mitigate future flooding. Report Page 1 of 10

2 Report Background on the July 27 and 28, 2014 storm: Typically the sewer system operates as designed and without incident. However, during and after rainfall events water can inflow and infiltrate into the sanitary sewers. These additional flows can use up sewer capacity and result in sewer surcharging and in extreme cases result in basement flooding. On the evening of July 27, 2014, and the following morning, a significant rain storm passed through St. Catharines. This was reflected in the data from the five rain gauges operated by the City. The greatest amount of rain was measured in south-west St. Catharines at the Pelham Road Fire Hall 6 site, which had millimetres (mm) of rain of which 17.5mm fell on July 27, 2014 and 51.2mm fell on July 28, The bulk of the precipitation fell in a 2 hour period from approximately 4:00am to 6:00am on July 28, 2014, where 42mm of rain fell. The rest of the City experienced significantly less precipitation: The downtown area had a total of 39.75mm, north St. Catharines had 36.25mm and the Merritton area saw 27.25mm. The Niagara Peninsula Conservation Authority operates a rain gauge on Twelve Mile Creek upstream of the Decew Hydro Generating Station near the St. Catharines and Pelham boundary. The site recorded 75mm of rain. The Region of Niagara operates a rain gauge at a wastewater pumping station in Vineland which recorded 96.5mm of rain. The information from these sites indicates that the rainfall amount recorded at the City s Pelham Road Fire Hall 6 site is comparatively the least amount of rain of the three sites and indicates that even higher amounts of rainfall was likely experienced to the south and west of St. Catharines. According to Environment Canada the average precipitation for the month of July is 77.8mm in St. Catharines. To put the July 27 and 28, 2014 storm in perspective it was over 88% of the total amount of rain that would typically fall in the entire month of July. Environment Canada also identifies the largest one-day rain fall event recorded in St. Catharines history as September 14, 1979 with 67mm of rain observed. St. Catharines has seen a number of large rain storms in the last two years. The following table shows the amount of rainfall in south-west St. Catharines. Table 1: Southwest St. Catharines has seen five large rain storms in the last two years. Date(s) Approximate Duration Volume of Rain observed at Fire Hall 6 (Pelham Rd) July 19 & 20, hours mm December 19-22, hours mm May 13 & 14, hours mm June 11, hours mm July 27 & 28, hours mm Report Page 2 of 10

3 Overall the July 27 and 28, 2014 storm resulted in significant amount rainfall across the City, but was quite localized with very high amounts of rainfall in south-west St. Catharines. It should also be noted that there are other factors which can contribute to flooding in addition to the amount of rainfall, for example saturated soil, rainfall patterns and frozen ground (applicable in the December, 2013 event). Investigation into the Causes of Basement Flooding Occurrences: As a result of the reported flooding a number of actions were undertaken to investigate the cause. This included flushing and inspecting the sewers using a variety of methods including: closed circuit television cameras (CCTV); a pole-mounted manhole camera; sewer connectivity testing using tracer dye; and smoke testing. It also involved reviewing the construction drawings for the sewers in the area to confirm the sewers were constructed as designed. All the sanitary and some storm sewers in the area were flushed prior to inspection. This ensured they were free of debris or deposits prior to other actions such as video inspections or smoke testing. The sanitary and storm sewers on Pelham Road from First Street Louth to Louth Street were inspected via CCTV. These inspections can identify structural and maintenance issues. A specialized pole-mounted camera was used to inspect many manholes and the connecting sewer pipes in close proximity to the manholes. This is an effective method to identify any maintenance issues near the manhole. However, this technique is limited to shallower sewers. City crews inspected the storm and sanitary sewers in the area to confirm both the sewers and catch basins are connected properly and to identify any cross connections between the storm and sanitary sewers. One of the inspection methods used to trace out the storm sewers in south-west St. Catharines involved using green and red dyes to trace out the flows. The dye is vegetable-based and non-toxic. Smoke testing consists of forcing a non-toxic coloured vapour into a sewer and noting where the vapours discharge and thus determining what is connected to the sewer being tested. Smoke testing has been used in the past in St. Catharines, but has not been used since the early 1980 s. In recent years there have been improvements in the technology which make it safer and more efficient. The City conducted smoke testing of the sanitary sewers in south-west St. Catharines. The objective was to identify any sanitary sewer line deficiencies and/or routes of infiltration to the sanitary sewer. Ten sewer flow meters were deployed in south-west St. Catharines in the fall of Sewer flow monitoring is designed to measure flows in selected areas of the sanitary sewer system, in order to better understand the systems performance. Report Page 3 of 10

4 Communications with Residents: The City undertook a number of actions to keep the area residents informed throughout the investigation. The first of these was preparing an information flyer for the neighbourhood. On August 15, 2014, the flyer was delivered to the approximately 1,800 properties in the area. A second flyer was delivered in mid-september prior to the start of the smoke testing. Several new pages were created on the City s website. This included general information on basement flooding as well as information specific to investigation and maintenance activities. Additionally a series of regular updates were posted to the website. It should be noted that not all incidents of basement flooding are reported to the City, this is especially true of properties which have not had a history of flooding and for which the damages are covered through homeowners insurance. For this reason a survey was delivered to 1,800 properties in southwest St. Catharines. Staff canvased door-to-door asking residents about their experiences with basement flooding. If residents were not at home a paid postage survey was left behind to complete and mail to the City. The City has received results from 773 of the approximately 1,800 residents that were surveyed (43%), which is generally considered to be a relatively high response rate. Results of the Investigations Survey Results: Of the 773 responses to the flooding questionnaire, 126 respondents (16%) indicated they had been flooded from the July 27 and 28, 2014 storm. Of those who flooded, 48% reported that the water came up through the floor drain, 28% reported that the water came up through their sump pump pit and 24% reported the source as being unknown. The majority of flooded respondents reported they were flooded with storm (clear) water (57%) with the remainder reported being flooded with sanitary sewage (34%) or unknown (9%). The amount of flooding related to sump pumps was not typical to other past flooding events in St. Catharines. Unlike flooding via a floor drain, sump pumps should not be directly connected to the sewers in the roadway. There are several possible reasons why flooding could occur via a sump pump: pump malfunction; a power failure; or the pump could be overwhelmed if the inflow exceeds the pump s capacity. This type of flooding would be consistent with a very large rain-storm resulting in a significant amount of groundwater entering weeping tiles. In fact it is possible that a sump pump configuration could work satisfactory in most situations, but be overwhelmed in a very large rain-storm. On multiple occasions while staff were talking to homeowners it was evident that there was a clear lack of understanding about how sump pumps operate and as well as their maintenance and discharge requirements. A large majority of homeowners have never replaced their sump pumps and in a few instances they were not functional. Report Page 4 of 10

5 Through numerous Flooding Alleviation Program (FLAP) assessments it was noted that very few properties had a sump pump backup system of any sort. Sump pumps do not work if there is a power failure unless there is a back-up system. In addition, improper discharge pipe configuration can cause sump pump failure. Examples of this include either freezing up in the winter or result in recirculation of weeping tile water, thus burning out the sump pump. There is also anecdotal evidence that some residents have redirected their sump pump discharge line from the surface into the sanitary sewer. This would be done inside their house (e.g. directing the line into their clean-out or plumbing stack). This is problematic for two reasons. First it is not allowed under the City s sewer use by-law as it results in groundwater flows entering the sanitary sewer. Secondly, if the sanitary sewer surcharges during a rainfall event the sump pump pit would fill with sanitary sewage and may end up flooding the home. Infrastructure Investigation Results: As part of the City s regular level of service, sanitary sewers are typically flushed once every five years. Sewers that have a history of heavier than normal deposition of debris are flushed on a more frequent basis, either annually or semi-annually. The level of service for the section of sanitary sewer upstream and downstream of the Pelham Road and Mac Turnbull Drive intersection is on a semi-annual maintenance schedule. The rest of the area is flushed on a five-year cycle. One of the reasons for the semi-annual maintenance on Pelham Road is the non-optimal sewer configuration at Mac Turnbull Drive. The sewer turns more than 90 degrees which has a negative impact on the hydraulic capacity of the sewer. The sewers in this part of the City were last flushed in 2009 and were scheduled to be flushed in Due to the flooding in July, the flushing was moved ahead in the priority list. A total of 18 kilometres of sanitary sewers in this area were flushed from mid-august to mid-september. The camera inspections and connectivity testing did not find anything that was atypical. This was consistent with the fact that the problems are related to rainfall, and that on a typical day the system operates without incident. Smoke Testing Results: The smoke testing investigation identified 58 potential locations where storm water could enter the sanitary sewer system. The majority of these were quite minor, for example a crack on the plastic cap of a sewer lateral cleanout. There were also several potentially more significant sources such as leaky manholes or sewers which would allow water to enter the sanitary sewer. Some of the identified locations are on City property (i.e. in the road allowance) and others are located on private property. For issues identified on private property, City Staff are working to contact the residents and will work with them to address any issues. An example of this could be a property with the downspouts connected into the sanitary sewer, which is not allowed under the City s Sewer-Use By-Law. Report Page 5 of 10

6 There are cases where issues on private property may not be able to be corrected, as they are voluntary actions at the homeowners discretion. For example if a house was built with the weeping tiles connected into the sanitary sewer it is grandfathered in the sewer-use by-law and is allowed to remain. As well if a sewer lateral is cracked or otherwise defective the City will complete the repair if it is on City property, but it is the responsibility of the homeowner to repair if on the private side. This is not mandatory and is the homeowner s decision (there is one property in the area where this is the case). For the issues on City property (within the road allowance); there are three types: 1. The first are relatively straight forward repair-type issues. For example repairing cracks at a manhole. City crews have assessed each of these sites and will be making the necessary repairs. 2. The second type of issue is those where further minor investigations are required to find the source. For example smoke may have been seen coming out of the ground in the boulevard indicating a cracked sewer lateral. In this case the sewer lateral would need to be inspected to find the exact location(s) that need to be repaired. These minor investigations are on-going. 3. The third type of issue is those with significant costs, for example sewer replacement or rehabilitation projects. Projects with significant budget impacts will be considered through the City s 2015 Capital Budget process. Valley Road was the only area where this type of issue was identified. Two culverts and a ditch were identified through smoke testing as moderate sources of inflow and infiltration. The smoke testing component of the investigation found a number of minor and moderate potential sources of storm water inflow and infiltration into the sanitary sewer system. It did not uncover a single source which would have accounted for the all flooding in July. However, the cumulative effect of all of these various sources would be considerable. Smoke testing effectively identified system deficiencies with minimal impacts and will be employed in the future where investigations of this nature are required. Consideration will be given to undertaking smoke testing in other parts of the City in the future, especially the sewers to the north of the current catchment area (i.e. downstream). The investigation found that there appears to be a high water table in much of the area which allows for a quicker response than would be expected into the storm and sanitary sewers when it rains. It also means that many sump pumps are constantly discharging groundwater to the surface, which can contribute to surface flooding during a rain event. In addition it also means that many sump pumps in the area are already working hard to keep groundwater away from the homes foundation, even during drier periods and may be more easily overwhelmed during heavy rain events, or flood quickly during periods of power outages. Report Page 6 of 10

7 Other actions the City has taken Manhole Inserts: City staff installed six manhole inserts along the north side of Pelham Road southwest of Mac Turnbull Drive. These inserts seal manholes, keeping rainwater out of the sanitary sewer that may otherwise flow through the lift holes in the manhole cover. Manholes situated near the gutter of the road were chosen, as they would be most susceptible to storm water inflow. Flood Alleviation Program: As previously reported to Council the FLAP Program has been in place since 1992 and currently offers a grant of up to $3,500 to offset the eligible costs a homeowner incurs related to the installation of basement flooding protection devices. These devices may include a mainline backflow prevention device installed on the building s sewer lateral, the disconnection of foundation drains (weeping tiles) from the sanitary sewer and reconnection to a sump pump, along with the required piping and electrical connections. FLAP assistance is not a solution for all types of flooding, but rather it can be an effective short term solution to main sewer surcharging. The previous report to Council regarding FLAP (August 11, 2014) is included in Appendix 1. In 2014 there were 137 homeowners who participated in the FLAP program with the large majority of those in this catchment area. In an average year the City would have approximately 15 FLAP applications. The FLAP program has been very successful with approximately 500 hundred properties benefitting from the City s assistance since the program began. Other Municipal Flooding Events The flooding that occurred in the south-west part of the City is not unique to St. Catharines. In the last two years at least 30 other Ontario Municipalities have had significant flooding occurrences. Some of the more prominent events include the July 2013 flooding in Toronto and the August 2014 flooding in Burlington. Key findings and Conclusions Typically the sanitary sewer system operates as designed and without incident. However, when it rains, storm water can find its way into the sewers. These additional flows can use up sewer capacity and may result in sewer surcharging and basement flooding. Based on the investigations outlined above, Staff believes the flooding in the urban area of south-west St. Catharines was caused by multiple factors including: a large rainfall event; debris in the sewers; storm water inflow and infiltration and sump pump failure. Large Rainfall: First the flooding was related to very large rainfall events. The rainstorm on July 27 and 28, 2014 resulted in almost a months worth of precipitation to fall in less than two days. It is important to note that this was the 5th large volume rainstorm in the last two years. Report Page 7 of 10

8 Debris in sewers: As a result of flushing the sewers in this area, debris was discovered and removed for proper disposal. During dry periods this is not an issue, as the sewers in this area are not flowing at their capacity. However, during large rain storms, storm water can enter the sanitary sewers and this is when anything that reduces the pipes capacity could become an issue. Storm water Inflow and Infiltration: Most of the sewers in this part of the City were built as a separate sewer system. This means there are sanitary sewers taking sewage to the wastewater treatment plants and storm sewers to take storm water to Twelve Mile Creek. Sanitary sewers are designed to carry sanitary flows with an allowance for some storm water inputs. This means that the sanitary sewers only have a limited capacity to transport storm water before their capacity is exceeded and surcharging may occur. The smoke testing component of the investigation found a number of minor and moderate potential sources of storm water inflow and infiltration into the sanitary sewer system. It did not uncover a single source which would have accounted for the all flooding in July. However, the cumulative effect of all of these various sources would be considerable. It should be noted that many of the findings could only be found using the smoke testing procedure. Sump Pump Failure: The amount of flooding related to sump pumps was not typical to other past flooding events. Unlike flooding via a floor drain, sump pumps are not directly connected to the sewers in the roadway. There are several possible reasons why sump pumps can fail, and there appears to be a lack of understanding by some residents about how sump pumps operate as well as their maintenance requirements. In addition, some sump pumps may have been re-directed to discharge into the sanitary sewer. When the sanitary sewers surcharge the sump pumps would not be able to work properly and can result in basement flooding. Conclusion Widespread basement flooding was reported throughout south-west St. Catharines due to a large, but localized rain storm on July 27 and 28, 2014 which saw almost 70mm of rain fall in this area, in approximately 16 hours. There were multiple factors that contributed to the flooding, including the combined effect of inflow and infiltration Had this much intense rain hit other parts of the City it is probable that they would have seen similar flooding. As a result while some parts of the action plan relate specifically to the area of flooding other actions are for City-wide implementation. It is unclear if this weather pattern is directly related to climate change, but it is one of five large volume rain storms the City has experienced in the last two years, all of which have resulted in basement flooding in this area. The flooding that was reported due to Report Page 8 of 10

9 the July 27 and 28, 2014 rainstorm was almost entirely in the south-west St. Catharines. However, a major factor was that this is where the greatest amount of rain fell. An action plan is listed below which includes enhanced maintenance activities; capital works projects, further investigations downstream and basement flooding prevention information for residents. Action Plan Enhanced Sewer Maintenance The sewers where debris was encountered should be re-flushed in This will ensure that the sewers are operating properly and confirm that there is no on-going source of debris. 2. Capital Works at Valley Road - To address the inflow and infiltration sources that were identified through smoke testing capital works projects are required in the Valley Road area. This includes re-lining the sanitary sewer and laterals with a tight fit liner to seal out storm water as well as drainage improvements to the storm water system. A diligent approach is required in terms of the storm water system so that the problem is not moved to another part of the City. 3. Capital Works at the Pelham Road / Louth Street / Mac Turnbull Drive intersection The sanitary sewers in this location require reconfiguration in order to improve the hydraulic capacity of the sewers. 4. Smoke Testing The sanitary sewers in this area of the City flow north and ultimately discharge to the Port Dalhousie Wastewater Treatment Plant operated by the Region of Niagara. Additional smoke testing will be undertaken to identify inflow and infiltration sources in other parts of the City, especially the downstream sewers to the north. Further reducing sources of storm water entering the sanitary sewers will improve the system performance and reduce the risk of future surcharging. 5. Pollution Control Plan The next Pollution Control Plan update is scheduled to begin in It would be appropriate to address how inflow and infiltration impact sewer performance on a City-wide basis. This would include evaluating the level of service for sewer maintenance, assessing the risk to sanitary and storm sewer systems due to climate change and developing a municipal flood response protocol. 6. Communications with residents This includes providing information and technical advice for residents to protect their homes from flooding. A basement flooding protection guide for residents is being developed by Staff. In addition, specific information will be prepared about the maintenance requirements for sump pumps and backwater valves. 7. Continuation of the FLAP Program Continue to offer the FLAP program to residents in this area, even if they may not have been impacted by recent flooding events. Implementation of the FLAP program to residents will provide them with greater individual protection while also reducing the amount of groundwater flows in the sanitary sewer system. Report Page 9 of 10

10 Financial Implications The costs to implement the items in the action plan can be accommodated in the proposed 2015 annual operating budget and 2015 wastewater budget. The capital works projects related to Valley Road Drive are included in the proposed 2015 capital budget. Prepared and Submitted: Mark Green Manager of Environmental Services Approved by: Dan Dillon, P.Eng. Director of Transportation and Environmental Services Report Page 10 of 10

11 1 Corporate Report Report from Transportation and Environmental Services, Environmental Services Date of Report: July 23, 2014 Date of Meeting: August 11, 2014 Report Number: TES File: Subject: Flood Alleviation Program Grant Limits Recommendation That Council direct that the St. Catharines Flood Alleviation Program s (FLAP) maximum grant be increased to $3,500 for eligible works; and That for FLAP grant applications that exceed $3,500, that the City contributes 50% of the eligible FLAP costs in excess of $3,500, at the discretion of the Director of Transportation and Environmental Services/City Engineer; and That the St. Catharines Flood Alleviation Program s application fee be waived until removed from the Rates and Fees by-law for 2015; and Further, that the City Solicitor be directed to prepare the necessary by-law. FORTHWITH Background At its meeting of July 21, 2014, Council received an earlier report from staff regarding Flooding Incidents at 302 Pelham Road Follow-up and referred to staff the following motion from Councilor Harris: That Council receive for information the report from the Transportation and Environmental Services Department, dated July 9, 2014, regarding Flooding Incidents at 302 Pelham Road Follow-up; and That the St. Catharines Flood Alleviation Program s maximum grant be increased to $8,500 for eligible works; and That the St. Catharines Flood Alleviation Program s application fee be waived until removed from the Rates and Fees by-law for Report Page 1 of 3

12 Report Flood Alleviation Program (FLAP) Grants Since 1992, the City has offered the FLAP to residents who have experienced basement flooding due to sewer surcharging. The FLAP program currently offers a grant of up to $3,000 which is used to offset the costs a homeowner incurs related to the eligible works. The eligible works may include a mainline backflow prevention device installed on the building s sewer lateral, the disconnection of foundation drains (weeping tiles) from the sanitary sewer and reconnection to a sump pump for discharge to the surface, along with the required piping and electrical connections. The total cost depends on the amount of work required as well as the layout and characteristics of the individual houses. Homeowners are required to obtain two quotes from qualified contractors for the work, and the grant amount is set at the lower of the two quotes. Additional costs above these are not included in the grant. Typically, the FLAP program covers all or almost all of the related costs, however, there have been cases in the past where the homeowner has been faced with a significant amount of out-of-pocket costs. The intent of the FLAP program is to subsidize the cost of the flood protection measures. The FLAP grant, authorized by Council, was originally capped at $2,500. In 2006, Council authorized the grant be increased to $3,000. Currently, a typical application is very close to or slightly above the $3,000 maximum. Since January 1, 2013, 23 grants have been approved through the FLAP Program. The grants have ranged between $1,215 and $3,000. Approximately 34% of all applicants have received the maximum grant ($3,000). Any costs which are above the $3,000 are paid for by the homeowner. If a homeowner needs to install a backflow prevention device, disconnect the foundation drains and install a sump pump, the cost would typically be around $3,300. Staff has reviewed recent contractor estimates and believe that the cost increase is due to higher costs for materials required to complete the work. Staff is also aware of a number of other municipalities who offer similar programs and found that St. Catharines limit is at the low end of the range. Regardless, the grant maximum of $3,000 is not always sufficient to cover the costs of the required works. In order to address this, staff believe that the maximum grant amount should be raised to $3,500. The grant can only be used to reimburse homeowners for approved expenses. While any grant limit is somewhat arbitrary, staff does not recommend raising the limit to $8,500. Most homeowners want to limit their out-of-pocket expenses as much as possible. Having a grant limit encourages homeowners to get the most competitive quotes they can get. Staff suspects that the average cost of a FLAP installation would rise more quickly if the limit was $8,500 compared to $3,500. Situations do arise when the required work is more complicated due to the layout of the building and the location of the sewer connections. Given that unique situations exist, it Report Page 2 of 3

13 may be Council s wish to have the City cover the additional costs related to eligible FLAP works. Should this be the case, a grant limit of $3,500 is still recommended. But when costs for the eligible works come in above the grant maximum, they would be addressed on a case by case basis. If that is Council s wish, it is recommended that the City pay 50% of any costs above $3,500, and that the authority to approve these additional expenses is delegated to the City Engineer / Director of Transportation and Environmental Services. There is a $150 application fee to apply for the FLAP program, and this fee has not changed since the program s inception. While this is an eligible cost and can be refunded through the FLAP grant, it can be a barrier to those who may want to apply. Staff recommend that the FLAP application fee be waived for future applicants. Financial Implications Should Council increase the maximum grant for the FLAP Program from $3,000 to $3,500, there would be a financial cost to do so. However, the number of homeowners applying for FLAP varies significantly from year to year and depends heavily on the number of extreme rainfall events. Currently, the number of requests for FLAP has exceeded the budgeted amount. In the 2014 Water and Wastewater budget, $28,000 was budgeted for FLAP grants. As of July 23, 2014, $32,800 has been spent on FLAP. Conclusion The FLAP program has been very successful with over four hundred properties benefitting from the City s assistance. The number of applications in any given year depends on the number of extreme rain events. FLAP assistance is not a solution to all types of flooding, but it can be an effective short term solution to main sewer surcharging. Increasing the maximum grant available through the FLAP Program will increase the likelihood that homeowners will not face out-of-pocket costs. Prepared and Submitted by: Mark Green Manager of Environmental Services Approved by: Dan Dillon, P.Eng. Director of Transportation and Environmental Services Report Page 3 of 3