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HomeMy WebLinkAboutDTS-08-034 - Upper Strasburg Creek - Class Environmental AssessmentREPORT Report To: DTS Committee, Chair - Christina Weylie Date of Meeting: March 3, 2008 Submitted By: K. Grant Murphy, P.Eng., Director of Engineering Prepared By: Binu J. Korah, P.Eng., Manager of Development Engineering Ward(s~ Involved: 4 -South Ward Date of Report: February 12, 2008 Report No.: DTS-08-034 Subject: Upper Strasburg Creek Class Environmental Assessment Report RECOMMENDATION: THAT the Upper Strasburg Creek Class Environmental Assessment Report prepared by CH2MHill and North-South Environmental Inc., dated January 2008 be received; and That the Upper Strasburg Creek Class Environmental Assessment Report be filed with the Ministry of Environment for the mandatory thirty X30} day review period as required by the Environmental Assessment Act. REPORT: In 2003, the City of Kitchener and the Grand River Conservation Authority (GRCA) with the participation of the Regional Municipality of Waterloo (Region) initiated the Upper Strasburg Creek Class Environmental Assessment (EA). The GRCA was the project lead on this project and the City is the proponent for this Class EA. The lands that are the focus of this Environmental Assessment (EA) are within the Upper Strasburg Creek Subwatershed, located in the southwest part of the City of Kitchener, upstream of Fischer-Hallman Road. The purpose of the EA is to resolve existing floodplain and major flow control issues in the upper subwatershed by determining which modifications are required to the Strasburg Creek culvert at Fischer-Hallman Road. Strasburg Creek currently crosses Fischer-Hallman Road through a very small culvert (900 mm) in a very high embankment and generates considerable backwater. The culvert cannot pass the Regional storm flows (Hurricane Hazel storm event). During Regional flow events, the backwater behind the culvert would flood considerable lands and several existing houses along Bleams and Fischer-Hallman Road. A Subwatershed Study update, which is the subject of a separate staff report, was also initiated concurrently with the EA to provide direction on how the lands should be graded and drained under future development conditions. The goal of the EA is to reduce the Regional flood level to 335 metre above sea level so that residences along Fischer-Hallman Road and Bleams Road are not subject to flooding under existing and future conditions. The stormwater management strategy for the upper subwatershed has identified flow control requirements such that existing flow rate conditions are maintained and the downstream aquatic habitats are not negatively impacted. During the EA process the following alternatives were considered. An analysis of each alternative was undertaken using technical, natural environmental, social and economic considerations; Alternative 1 -Replace existing 900 mm culvert with a lar_. er culvert Alternative 1 would reduce the Floodline below 335 metres and maintain the existing Regional peak flow below 12.7 m3/s. However, the larger culvert would allow more discharge downstream under a number of storm events than compared to current conditions, which could negatively impact the downstream stream habitat. Alternative 2 -Maintain the existing 900 mm culvert and add a high level overflow culvert s Alternative 2 would reduce the Floodline below 335 metres and maintain the Regional peak flow below 12.7 m3/s. The culvert discharge would only differ from existing conditions under a Regional storm event. Alternative 3 -Replace existing 900 mm culvert with a similar sized culvert and add a high level overflow culvert(s) Alternative 3 provides all the benefits of Alternative 2, with the increased structural stability of a new culvert. Alternative 4 - Do nothin Alternative 4 maintains the status quo, meaning the existing flood risk would remain. Alternative 3 was selected as the preferred alternative. The preliminary design includes the replacement of the 900 mm culvert and the addition of two Corrugated Steel Pipe (CSP) pipes that are 1800mm in diameter which will be installed above the 900 mm culvert, (see attached Figure). The final length of the culverts should consider a future road widening of Fischer- Hallman Road. The new culvert invert elevation will be set at the existing culvert invert. Erosion protection will be provided at the downstream end of the culvert consisting of riprap and stream bank stabilization/bioengineering to mitigate the impacts of the flow discharge under a Regional event. A preliminary cost of $83,837 has been estimated for the undertaking. The Region, as road authority for Fischer-Hallman Road, will be responsible for the construction of the culvert upgrade. Potential environmental impacts and proposed mitigation measures are outlined in the report and this should be considered during the detailed design stage. In terms of implementation, the culvert replacement must be constructed prior to any development upstream of Fischer-Hallman Road, south of Gleams Road. The culvert replacement is currently forecasted in the Region of Waterloo Transportation Capital Budget Program for 2013. It is recognized that the Middle Strasburg Creek sanitary sewer, a City project, is planned to cross Fischer-Hallman Road at the same location as the culvert. The EA recommends that these two projects be undertaken at the same time. Any future development will be required to control their stormwater to ensure that there is no increase in the Regulatory Floodline. The EA also provides direction for future development based on an analysis of various development scenarios. It is recommended as part of the overall drainage strategy that the existing recharge rates should be maintained, the hummocky terrain should be maintained as much as possible along greenbelt routes and that multiple stormwater management ponds be developed in the Upper Strasburg Creek Subwatershed. These recommendations in conjunction with the recommendations of the companion document, the Alder Creek Watershed Study and Upper Strasburg Creek Subwatershed Study update, will form the management strategy for future development in the Upper Strasburg Creek Subwatershed. Staff recommend that the Upper Strasburg Creek Class Environmental Assessment Report be filed at this time as it represents a viable solution to resolve floodplain and major flow control issues under existing conditions. The City is planning to re-initiate the Strasburg Creek Flood Control Class EA by April 2008. During this Class EA, the stormwater management requirements for Regional control in the Upper Subwatershed and sizing of the Fischer-Hallman culvert will be re-evaluated. If the outcome of Strasburg Creek Flood Control Class EA provides a better water management alternative for the Upper Strasburg Subwatershed than the current EA, then that alternative will be implemented. Consideration may also be given to including atrail-sized culvert to connect future community trails along Strasburg Creek east and west of Fischer-Hallman Road. COMMUNICATIONS: One Steering Committee oversaw both the EA and the Alder Creek Watershed Study and Upper Strasburg Creek Subwatershed Plan update. Members included staff from the City of Kitchener, Regional Municipality of Waterloo, GRCA, Ministry of Natural Resources, County of Oxford and the Township of Wilmot. Two public open houses were conducted for this EA; one in July, 2003 and another in March, 2007.On January 25, 2008, the GRCA General Membership approved the Upper Strasburg Creek Class Environmental Assessment Report. FINANCIAL IMPLICATIONS: No financial implications to the City. The construction of the culvert upgrade will be the responsibility of the Regional of Waterloo. Further, this project was identified in the 2008 Regional Capital Budget Forecast to construct in 2013 with development charge funds. CONCLUSION: The City of Kitchener in partnership with the GRCA have undertaken a Schedule B, Class Environmental Assessment in order to resolve existing flooding concerns in the Upper Strasburg Creek Subwatershed within the southwest part of the City of Kitchener. The preferred solution is to replace the existing 900 mm culvert on Fischer-Hallman Road with a new 900 mm culvert and the addition of overflow culverts to pass the Regional storm event. The Regional Municipality of Waterloo will be responsible for the implementation of this project. The Staff recommend that Council allow the Upper Strasburg Creek Class Environmental Assessment Report be filed with the Ministry of Environment for the mandatory thirty (30) day review period as required by the Environmental Assessment Act. Binu J. Korah, P. Eng., Manager, Development Engineering K. Grant Murphy, P. Eng., Director, Engineering Services