Carruthers Creek Flood Management & Analysis Municipal Class EA Project No. W10 288

Transcription

1 Carruthers Creek Flood Management & Analysis Municipal Class EA Project No. W May 2012

2 Table of Contents 1.0 Introduction Background Roles and Responsibilities of Agencies Ministry of Natural Resources Toronto and Region Conservation Authority Town of Ajax Flood Messages Introduction Watershed Conditions Statement (High Water Safety Bulletin) Flood Watch (Flood Advisory) Flood Warning Flood Response Procedures Introduction Response Stages Stage One: Monitoring Stage Two: Heightened Level of Risk Stage Three: Rising Water Levels and Imminent Flooding Communication Termination of Emergency Notification Debriefing Future Development and the FEPP... 9 LIST OF FIGURES Figure INSP INSPECTION AREAS Figure EMERG EMERGENCY ACCESS ROUTES Following Report Following Report LIST OF TABLES Table 4 1 Monitoring Locations...5 W (May 2012) Page i

3 Town of Ajax APPENDICES Appendix A Statement of Limiting Conditions and Assumptions W (May 2012) Page ii of 9

4 1.0 Introduction This (FEPP) has been prepared to outline steps for monitoring and responding to emergency conditions arising from high water levels of Carruthers Creek within the Town of Ajax (the Town). This plan is a framework that ensures the Town is prepared for the possibility of flooded public and private properties as a result of high water levels during an extreme flooding event similar to Hurricane Hazel in the 1950 s. This event is called the Regional Storm in this part of Southern Ontario. The Flood Response outlines a response to a Regional Storm under the existing conditions. The Toronto and Region Conservation Authority (TRCA) and the surrounding Greater Toronto Area (GTA) conservation authorities operate under the guidance of the 2008 Provincial Flood Forecasting and Warning Implementation Guidelines, to reduce the risk to life and damage to property due to flooding. This is done by providing local agencies and the public with notice, information, and advice so that they can respond to potential flooding and flood emergencies. This plan is intended to be used as a tool to support and coordinate with the existing Town of Ajax Emergency Response Plan (2007) and the TRCA Flood Contingency Plan (2009). The plan considers a variety of stages and is triggered by information provided by the TRCA, the Ontario Ministry of Natural Resources (MNR) and information gathered by the Town Background In 2010, the TRCA prepared an update of the Regional Storm flood lines within the Carruthers Creek Watershed. Within the Town this update meant an increased number of properties within the regulatory flood limit as well as a potential spill risk through the Pickering Beach neighbourhood. The Town acquired the professional services of Cole Engineering Group Ltd. (Cole Engineering) to perform a Schedule C Municipal Class Environmental Assessment (Class EA). The scope of the Class EA was to recommend a solution that would eliminate or mitigate the spill through the Pickering Beach neighbourhood without putting additional properties at risk. A flood control landform with local lowering of the floodplain was determined to be the preferred solution that best met the problem and opportunity statement. Until the installation of the flood control landform this plan will provide guidance to Town personnel in the event a Regional Flood occurs. Further information about the Class EA can be found in the Environmental Study Report completed by Cole Engineering in Cole Engineering also updated the hydrology model for the Carruthers Creek Watershed as a part of the Class EA. This resulted in a considerable decrease in peak flows within the watershed with a Regulatory flow reduction of approximately 35% at Shoal Point Road. The results of this hydrology modeling are summarized in the Hydrology Update Report Carruthers Creek Watershed completed by Cole Engineering in Roles and Responsibilities of Agencies This section will discuss the roles and responsibilities of the MNR, the TRCA and the Town. These three (3) groups have separate methods of monitoring water levels and will work together to coordinate W (May 2012) Page 1 of 9

5 timely public notifications and to ensure the public is protected from risk due to flooding, which includes water levels and flows (velocity and depth together) Ministry of Natural Resources The role of the MNR is to liaise with the TRCA and the Town regarding flood advisories, warnings and updates. The MNR operates the Surface Water Monitoring Centre that collects and analyzes water flows, levels, and climate data. The centre identifies sensitive and risk prone areas throughout the province. With this data the monitoring centre, along with the MNR, will provide flood forecast messages on a Provincial / Regional scale. These do not always translate to the local level Toronto and Region Conservation Authority The role of the TRCA is to monitor the watershed and weather conditions and operate a flood forecasting system in order to provide warning of anticipated or actual flood conditions from the Weather Office at Environment Canada and other sources to predict the potential for flooding across their jurisdiction. It is important to note that the messages that are issued are also covering broad areas and it is unlikely that a community specific message will be issued. The TRCA is responsible for issuing Watershed Conditions Statement, Flood Watch, and Flood Warning bulletins to all key contacts within the jurisdiction, including upper and lower tier municipalities, emergency services, school boards, weather networks, the MNR, and media outlets. The TRCA currently has a stream gauge at Achilles Road. This gauge is part of TRCA s real time flood monitoring network Town of Ajax The Town has the responsibility and authority for response to flooding and flood emergencies, welfare of residents, and protection of property. The responsibility of the Town s Operations personnel is to: Notify appropriate officials, departments, and agencies in accordance to their emergency plan including the fire department if evacuation is required of residents; Deploy municipal resources to close roads and bridges and determine the evacuation route; Respond to the flood emergency notice from the TRCA; Respond to flood notification from residents; Assess the impact of the flood emergency; Monitor Table 4 1 locations and take appropriate action as listed in the table; and, Maintain liaison with the TRCA. Detailed steps to be taken by the Town will depend on water levels and are further detailed in Section 4.0. This should also be paired with the Town s Emergency Response Plan (2007). W (May 2012) Page 2 of 9

6 3.0 Flood Messages 3.1. Introduction The MNR and the TRCA are responsible for issuing flood forecasting messages. The MNR maintains a Surface Water Monitoring Centre that is linked to a network of weather stations, stream gauges, and rain gauges throughout the province. They have a 7 day, 24 hour provincial notification procedure that they maintain and would issue to the TRCA and the Town. Since the Town is within the TRCA jurisdiction, most of the local flood forecasting will be done by the TRCA with some assistance from the MNR. The southern portions of the Carruthers Creek watershed are largely developed with Taunton Road as the northern development limit. Areas north of Taunton Road are mainly undeveloped and comprise of agricultural lands and natural areas. As a result, the northern undeveloped portions of the watershed cause the watershed to have a lower peak flow response than would be observed in a largely urbanized watershed. Based on measured precipitation and stream flow it appears that the watershed responds to rainfall events within five (5) hours from the start of precipitation with the peak flows observed approximately five (5) to ten (10) hours after the measured peak rainfall intensity. The Regional Regulatory Storm for this area (Hurricane Hazel) is characterized by thirty six (36) hours of light rainfall that saturated the ground, followed by 12 hours of more intense rainfall. Based on this rainfall distribution hydrologic modelling indicates that the peak flow will reach the spill point of Carruthers Creek approximately 11 hours after the intense rainfall begins (approximately 47 hrs into the Hurricane Hazel event). Spill is estimated to occur through Pickering Beach beginning at 9.4 hours after the start of intense rainfall (45.4 hrs into the Hurricane Hazel event) with a duration of approximately 4.6 hours Watershed Conditions Statement (High Water Safety Bulletin) A Watershed Conditions Statement is a general notice of weather that poses a risk to personal safety or that has the potential to lead to flooding. It may be issued when streams are flowing at full capacity levels, when ice conditions are unsafe, or when stream banks are icy, soft, and / or slippery. Conditions such as these will be assessed by the TRCA and the bulletin will be issued to the Town Flood Watch (Flood Advisory) If the TRCA determines that there is a potential for flooding a Flood Watch message will be distributed to the Town. The message is intended to provide the Town enough notice if flooding is possible in specific watercourses or municipalities. Municipalities, emergency services, and individual landowners in flood prone areas should prepare. A Flood Watch can be updated depending upon weather and runoff conditions. Once the potential for flooding has passed a notice of cancellation will be released by the TRCA. W (May 2012) Page 3 of 9

7 3.4. Flood Warning Once a flood is deemed imminent or occurring, the TRCA will issue a Flood Warning notice. This provides notice to the Town s Operations and Fire and Emergency Services that will be required to take appropriate action. Flood warnings can be updated depending on weather conditions, and will be followed by a notice of cancellation. Action may be taken by the Town before a Flood Warning. 4.0 Flood Response Procedures 4.1. Introduction This outlines the action to be taken in the event of a flood under existing conditions. This includes steps to respond to the identified spill through the Pickering Beach neighbourhood. It has been identified that there are twenty two (22) homes with a population of approximately fifty three (53) people (2.4 people / home as per Town standards) affected Response Stages Stage One: Monitoring In the event that the Town receives a Watershed Conditions Statement (High Water Safety Bulletin) the Town is to remain in communication with the TRCA until the next level of messages is released. Depending on the severity and / or rate at which water is expected to rise, the Town can choose to post a flood message on their website Stage Two: Heightened Level of Risk If the water levels continue to rise and a Flood Advisory Message is released by the TRCA, the Town is to take the following steps: Maintain flood emergency information on the Town s website; Ajax Municipal Operation Centre personnel will monitor / inspect flood prone areas (outlined in Figure INSP following the report); Follow the Town s communication protocol from the Town s Emergency Response Plan; Anticipate, plan and conduct public awareness sessions as needed; and, Identify populations at risk (Figure EMERG following the report). At this stage it is important that the Town maintains direct communication with the TRCA in order to better understand the rate at which the water level is expected to rise. The critical inspection locations that are outlined in Figure INSP, following the report, will help the Town to monitor rising water levels and determine when further steps need to be taken. W (May 2012) Page 4 of 9

8 Stage Three: Rising Water Levels and Imminent Flooding As outlined in Section 3.3 a Flood Warning will be released when the TRCA deems the flood to be imminent or occurring. Under existing conditions the flooding will begin to occur through a large, empty property on Beachview Street, through the backyards and properties on Seabreeze Road and other lowlying areas, see Figure INSP following the report. Before this occurs, it is important to monitor water levels and flows in these areas. The Town s Operations and Fire and Emergency Services will notify all the affected residents. Ruthel Road, just south of Seabreeze Road to Ebony Street will need to be closed to private vehicles and pedestrian traffic when water levels rise to 0.2 m and closed to emergency vehicles when water levels reach 0.3 m, as per Town standards. Emergency services need to be notified prior to water levels on Shoal Point Road bridge reaching 0.3 m, when the bridge needs to be closed to emergency vehicles. Emergency access can be gained to the Pickering Beach neighbourhood through Beachview Street. Proper warning through the use of road signs needs to be in place in accordance with the MTO standards. The Town s Operation s personnel will be responsible for placement of signs and closing of roads. Table 4 1 below contains a general overview of the inspection points and actions to be taken by the Town s Operations personnel when water levels reach a critical level. The point number coordinates with the numbers in FIGURE INSP, following the report. Beachview Street will experience flooding at its east end near the marsh. The flooding depths will be greater than 0.9 m and so will have to be closed to all vehicles, including emergency vehicles right at its eastern end, see Figure EMERG following the report. Table 4 1 Monitoring Locations Point Description Elevation (m) Action Notes 1 2 Ruthel Road at Ebony Street Ruthel Road at Range Line Road (at road centreline) (at road centreline) In the event of a Regional Storm, velocities can be as high as 0.13 m/s with water levels reaching m (0.53m deep). When water levels reach 0.2 m at this location, proceed with closure of the intersection with access only to emergency vehicles. This location will also have to be closed for emergency vehicle access when water levels reach 0.3 m. In the event of a Regional Storm, water levels can rise to m (0.48 m deep) with velocities up to 0.40 m/s. When water levels reach 0.2 m at this location, proceed with closure of the intersection with access only to emergency vehicles. This location will also have to be closed for emergency vehicle access when water levels reach 0.3 m. Due to high water levels and flows, Ruthel Road should be closed south of Seabreeze Road to Ebony Street (with the exception of emergency vehicles) when water levels rise to approx. 0.2m, or when the Town deems the road unsafe for public use. When the water levels rise to 0.3 m the road will also have to be closed for emergency vehicle access. W (May 2012) Page 5 of 9

9 Point Description Elevation (m) Action Notes Ruthel Road at Seabreeze Road Seabreeze Road SW corner of 2922 Beachview Street East end of Beachview Street North border of easement beside pump house (at road centreline) (low point of Seabreeze Road centreline) (end of street at marsh) 78.3 In the event of a Regional Storm, velocities can be as high as 0.40 m/s with water levels reaching m (0.33 m deep). When water levels reach 0.2 m at this location, proceed with closure of the intersection with access only to emergency vehicles. This location will also have to be closed for emergency vehicle access when water levels reach 0.3 m. In the event of a Regional Storm, water levels can rise to 78.65m (0.53 m deep). As water levels rise they will become a hazard for residents that surround this lot. A Regional Storm event can cause waters to rise to m (1.69 m deep). Water levels at this location can reach as high as m (1.12 m deep). Due to high water levels Beachview Street should be closed to all public vehicles when water depths reach 0.2 m and all vehicles including emergency vehicles when water levels reach 0.3 m. Monitor to ensure no structural damage done to pump house. When water levels reach 0.2 m at this location, proceed with closure of the intersection with access only to emergency vehicles. This location will also have to be closed for emergency vehicle access when water levels reach 0.3 m. The Town should ensure that residents in this area are informed of imminent flooding when water levels reach 0.8 m at this location. Flood waters will start to rise to the backyards of some residents and possibly to any structures on the land. Region of Durham responsibility W (May 2012) Page 6 of 9

10 Point Description Elevation (m) Action Notes 8 Shoal Point Road Bridge 77.0 Monitor upstream of the bridge to ensure no structural damage due to high flows and debris. In a Regional event the bridge will become overtopped by a depth of 1.29 m. It is imperative to close bridge to public access when water depths reach 0.2 m, and close to emergency access when depths reach 0.3 m. 9 Rollo Drive at Hewitt Crescent m to m Water levels are expected to rise to m. Monitor water levels. Water may rise to house borders on some lots. Due to high water levels Lakeview Boulevard should be closed to all public vehicles when water depths reach 0.2 m. 10 End of Callander Court 79.4 Monitor water levels. Water may rise to house foundations on some lots. 11 Shoal Point Road at Warbler s Swamp Varies ( ) Water levels will reach a maximum of m along this stretch of Shoal Point Road (approximately Spiers Crescent to Salt Drive). When water levels reach 0.2 m at this location, proceed with closure of the intersection with access only to emergency vehicles. This location will also have to be closed for emergency vehicle access when water levels reach 0.3 m Bayly Street, West culvert Bayly Street, East culvert 79.1 (culvert invert) (81.6 at road) 79.0 (culvert invert) (82.3 at road) Water levels are expected to rise to m during the Regional Storm, which will overtop Bayly Street by 0.27 m at this location. Monitoring should be done to ensure there is no structural damage done to the culvert / road. The Region should close and inspect the Bayly Street bridge for structural damage when water levels exceed 0.2 m. Water levels are expected to rise to m during the Regional Storm, which will not overtop the road at this location. Monitoring of this location should be done to ensure there is no structural damage done to the culvert / road. Water is not expected to overtop at this section of the road. The road should be monitored for structural damage. W (May 2012) Page 7 of 9

11 Point Description Elevation (m) Action Notes 14 Lakeview Boulevard 76.0 Water levels are expected to rise to m. Due to high water levels Lakeview Boulevard should be closed to all public vehicles when water depths reach 0.2 m. The Town will need to have a member (or team) monitor the status of critical infrastructure as well as inspect the flooded areas to determine the extent of damage. Inspected critical infrastructure should include public utilities, watermains, sanitary and storm sewers, roads and sidewalks, publicly owned buildings, and the Shoal Point Road bridge. A general list of required tasks for Stage Three (3) includes: Alert appropriate residents and services; Escalate monitoring / inspection of flood prone areas; Initiate evacuation of structures, as required; Restrict / close access to appropriate roads; and, Monitor status of critical infrastructure Communication It is important for the Town s Fire and Emergency Services to be in communication with the residents through the Town s website and emergency services that are within the floodplain to educate them on the steps outlined in the plan and their responsibilities and required actions to be taken in the event of a flood emergency evacuation. The Town s Fire and Emergency Services shall contact residents whose property is within the floodplain as outlined in Figure EMERG following the report. Residents need to understand the steps the Town will take at each stage of flooding, and should be told to contact the Town or TRCA if they have further questions. 5.0 Termination of Emergency 5.1. Notification If water levels start to decline or the intensity of the storm was not as strong as expected the TRCA can change the status of the flood warning message. For this reason it is important to maintain communication with the TRCA, the MNR, and for the Town to monitor water levels. When the level of warning is downgraded, the Town should post the update on the website and if necessary notify residents. The Town will also post road closures and when roads are to be reopened on their website, or use other sources of media to communicate the updates. Notification is to be sent to all emergency services and appropriate personnel should be updated of roads reopening and public property that sustained flood damage. W (May 2012) Page 8 of 9

12 5.2. Debriefing Once any risk of flooding has been removed the Town can concentrate on repairing any damaged structures and offering support to residents. The Town is responsible for opening up roads that had been closed once water levels have declined and the road has been inspected and approved for safe public use. This also is the case for the Shoal Point Road bridge. During a Regional Flood event the bridge will be overtopped by over a metre of water and subject to high flows. This may cause structural damage and put the integrity of the bridge at risk. The Town s Engineering Services and Operation s roads crews should thoroughly inspect the bridge and ensure that it is safe for use before opening. The Town and the Region of Durham are also responsible for ensuring the regular operation of utility, watermain, sanitary and storm sewer networks. Inspections should be done for sanitary and storm sewers in the Pickering Beach neighbourhood and in the floodplain valley. Any publicly owned properties (specifically the pump house located on Mayor Crescent) should be inspected and any damage should be repaired. Stormwater management facilities should also be inspected to ensure that they did not sustain any damage. Any damage to private property within the floodplain as a result of flooding is to be repaired by the owner. It is the Town s responsibility to ensure the safety and well being of its residents, however houses in the floodplain are warned to expect flooding and will need to go through their insurance company and / or the TRCA to deal with complaints. 6.0 Future Development and the FEPP The FEPP has identified procedures associated with potential flooding identified by the approved land uses established in the current official plans. Should flood flows or elevations be impacted as a result of future development, this FEPP should be revisited to ensure emergency access, et cetera is available. W (May 2012) Page 9 of 9

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15 APPENDIX A Statement Of Limiting Conditions And Assumptions

16 Statement of Limiting Conditions and Assumptions 1. This Report/Study (the Work ) has been prepared at the request of, and for the exclusive use of, the Owner, and its affiliates (the Intended Users ). No one other than the Intended Users has the right to use and rely on the Work without first obtaining the written authorization of Cole Engineering Group Ltd. (Cole Engineering) and its Owner. 2. Cole Engineering expressly excludes liability to any party except the Intended Users for any use of, and/or reliance upon, the Work. 3. Cole Engineering notes that the following assumptions were made in completing the Work: a) the land use description(s) supplied to us are correct; b) the surveys and data supplied to Cole Engineering by the Owner are accurate; c) market timing, approval delivery and secondary source information is within the control of Parties other than Cole Engineering; and d) there are no encroachments, leases, covenants, binding agreements, restrictions, pledges, charges, liens or special assessments outstanding, or encumbrances which would significantly affect the use or servicing. Investigations have not been carried out to verify these assumptions. Cole Engineering deems the sources of data and statistical information contained herein to be reliable, but we extend no guarantee of accuracy in these respects. 4. Cole Engineering accepts no responsibility for legal interpretations, questions of survey, opinion of title, hidden or inconspicuous conditions of the property, toxic wastes or contaminated materials, soil or sub-soil conditions, environmental, engineering or other factual and technical matters disclosed by the Owner, the Client, or any public agency, which by their nature, may change the outcome of the Work. Such factors, beyond the scope of this Work, could affect the findings, conclusions and opinions rendered in the Work. We have made disclosure of related potential problems that have come to our attention. Responsibility for diligence with respect to all matters of fact reported herein rests with the Intended Users. 5. Cole Engineering practices engineering in the general areas of infrastructure and transportation. It is not qualified to and is not providing legal or planning advice in this Work. 6. The legal description of the property and the area of the site were based upon surveys and data supplied to us by the Owner. The plans, photographs, and sketches contained in this report are included solely to aide in visualizing the location of the property, the configuration and boundaries of the site, and the relative position of the improvements on the said lands. 7. We have made investigations from secondary sources as documented in the Work, but we have not checked for compliance with by-laws, codes, agency and governmental regulations, etc., unless specifically noted in the Work. 8. Because conditions, including capacity, allocation, economic, social, and political factors change rapidly and, on occasion, without notice or warning, the findings of the Work expressed herein, are as of the date of the Work and cannot necessarily be relied upon as of any other date without subsequent advice from Cole Engineering. 9. The value of proposed improvements should be applied only with regard to the purpose and function of the Work, as outlined in the body of this Work. Any cost estimates set out in the Work are based on construction averages and subject to change. 10. Neither possession of the Work, nor a copy of it, carries the right of publication. All copyright in the Work is reserved to Cole Engineering. The Work shall not be disclosed, produced or reproduced, quoted from, or referred to, in whole or in part, or published in any manner, without the express written consent of Cole Engineering and the Owner. 11. The Work is only valid if it bears the professional engineer s seal and original signature of the author, and if considered in its entirety. Responsibility for unauthorized alteration to the Work is denied.