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HomeMy WebLinkAboutINS-11-051 - City of Kitchener 2010 Wastewater Capacity Study1 Staff Re ort p Krr~.~-~~,i~iER ~nfrastru~ture Servrces Department www.kitthenerta REPORT TO: Community and Infrastructure Services Committee DATE OF MEETING: May 30, 2011 SUBMITTED BY: Grant Murphy, Director, Engineering Services - 2410 ~ PREPARED BY: Greg McTaggart, Manager, Infrastructure Asset Planning - 2634 WARD(S) INVOLVED: All DATE OF REPORT: May 19, 2011 REPORT NO.: INS-11- 051 SUBJECT: CITY OF KITCHENER 2010 WASTEWATER CAPACITY STUDY RECOMMENDATION: That the final report regarding the findings of the City-wide Sanitary Sewer System Capacity Study conducted by AECOM Canada Ltd. consultants be accepted, and that recommendations for sanitary sewer system upgrades contained within the report be taken into consideration by staff in the capital budget's 10-year forecast. EXECUTIVE SUMMARY: In November of 2009 the City of Kitchener retained AECOM Canada Ltd. to perform a City Wide Sanitary Sewer System Capacity Study. The purpose of the study was to: • Evaluate available capacity and performance of the City's existing sanitary sewer network, both currently and the system's ability to accommodate future growth scenarios • Identify potential constraints in the system, both currently and under future growth scenarios and identify remediation strategies • Facilitate best practice in infrastructure asset management now and in the future by enhancing growth planning of the sanitary sewer system • Provide the City with a hydraulic computer model of the sanitary drainage system that can be operated by staff on an ongoing basis Project work was substantially completed in October of 2010, with the primary products of the study being a 730 page report of the findings and recommendations for improvements to the sewer network relating to system capacity, and a computer dynamic hydraulic model of the City's entire sanitary sewer network. The hydraulic model will be used as a comprehensive tool to evaluate sanitary sewer network system performance. It will also enable staff to evaluate the impact of development proposals and potential future zoning changes on the sanitary sewer network. This ability will become increasingly important into the future, as the Provincial "Places To Grow" Growth Plan stipulates that a significant portion of future development in Kitchener must take place with the current is - i 1 Staff Re ort p Krr~.~-~~,i~iER ~nfrastru~ture Servrces Department www.kitthenerta urbanized area of the municipality. The City has prepared a Growth Management Strategy to further identify specific intensification areas for potential development under the current zoning. One of the applications of this Capacity Study is to support the implementation of the Kitchener Growth Management Strategy and the creation of the City's new Official Plan. BACKGROUND: In past years, the City of Kitchener has undertaken various studies of portions of its sanitary sewer system in order to better understand functional capacity and overall performance within specific areas of the system. Following on from this, the City retained AECOM consultants in November 2009 to create a computer hydraulic model of the City's sanitary sewer network and then use it to perform acity-wide sanitary sewer system capacity study. The City's sanitary sewage collection system includes approximately 735km of sewer mains and 24 sewage pumping stations all discharging to a single treatment plant operated by The Region of Waterloo. The City's system also has multiple connections to neighbouring municipalities including townships of Wilmot and Woolwich, and the cities of Waterloo and Cambridge. The computer model uses InfoSWMM, a software application, and the City's GIS data to simulate the operation of the entire sanitary sewer network under a wide range of conditions. A primary output from this model is how much sewage the system is conveying at any given location in the network, and how much additional capacity the system has to accommodate additional sewage volumes. The model was then used as a tool to perform a study on a city- wide scale of the City's sanitary sewer system capacity currently and what capacities may be required of the system by sewage volumes generated by future urban growth. This will facilitate best practices in infrastructure asset management now and into the future by facilitating planned and budgeted sanitary sewer system upgrades that will address capacity requirements. Specific objectives of the study were as follows: • Conduct a detailed background data collection and review • Develop and calibrate a hydraulic model of the existing sanitary sewer system • Undertake an extensive flow monitoring program and data analysis intended to measure actual system performance and calibrate the computer model • Assess the capacity of the existing sanitary collection system • Identify the system constraints under defined future growth scenarios • Develop and evaluate mitigative measures to address existing issues and service new growth. REPORT: Four operating scenarios were studied for the City's sanitary sewer network: current sanitary sewer system capacity and performance, theoretical future flows based on percentages of the potential capacity to accommodate population densities under current zoning identified in the Kitchener Growth Management Strategy (50%, and 100%), and lastly flows generated by a theoretical full build out to current zoning capacity (a city population of 511,000}. With each scenario, the calibrated hydraulic model was used with a 25yr, 12hr AES design storm to evaluate available capacity within the existing sanitary sewer system in a "worst case" scenario. As part of the Background Study to the Kitchener Growth Management Strategy, the City estimated how much population and employment growth could be accommodated under current 2 1$-2 1 Staff Re ort p Krr~.~-~~,i~iER ~nfrastru~ture Servrces Department www.kitthenerta zoning conditions. Several assumptions were used to prepare scenarios that calculated the potential increase in new dwelling units, persons, non-residential floor space, jobs and density primarily located within Intensification Areas while maintaining existing, stable neighbourhoods. The scenarios investigated the capacity to accommodate growth up to 50% of the maximum density that the zoning permitted within those areas and up to 100% of that maximum. The City provided a copy of these background estimates to AECOM to utilize in running sample "what if" modeling scenarios to the current flow/capacity of the sanitary sewer system. The expectation is that the sanitary sewage network should reasonably be able to accommodate growth in certain areas of the city under the current zoning. Pipe Nefwork: The study has identified 156 conduits (pipes) with genuine capacity concerns in the existing sewer system, 209 for the 50% KGMS growth scenario, and 237 for a build out up to the 100% KGMS growth scenario were taken forward for further consideration. Although this may seem a significant figure, for comparison there are over 11,500 pipe segments that comprise the City's sanitary sewer network as a whole. These identified conduits can be grouped into 18 specific problem areas. Using the calibrated hydraulic model, mitigation measures to alleviate these concerns and provide additional capacity up to the 100% scenario were identified, costed and prioritised for implementation depending on the extent of surcharge and timeframe when these capacity constraints are first exhibited. Figure 1 below illustrates locations and extents of capacity concerns requiring mitigation identified for the current, 50% KGMS, and 100% KGMS build out. Appendix "A" lists the locations in greater detail along with cost estimates. Figure 1: Illustrating the locations and extents of sanitary sewer network capacity concerns and the timing of when these locations are expected to become of concern, in terms of the current (existing) situation, 50% KGMS build out, and 100% KGMS build out. 18-3 1 Staff Re ort p Krr~.~-~~,i~iER ~nfrastru~ture Servrces Department www.kitthenerta The last scenario modeled was a full build out to current zoning. Should the City allow development up to the current zoning capacity, large areas of the existing local and trunk sewer system will have insufficient capacity to accommodate these theoretical flows. It must be noted that this would not occur for a very significant period of time, if at all. The consultant has however noted as well that the City's existing design specifications for sewage quantities generated per person is very conservative, and revisiting those specifications may well show additional capacity in the system in general not currently permitted for use. This is an activity planned as a follow-up to the study. Sewage Pumping Stations: From the analysis it was determined that four of the City's sanitary sewage pumping stations have capacity concerns regarding their ability to accommodate existing sanitary flows. These facilities are: Homer Watson, King St East, Old Mill, and Bleams Road. The Homer Watson facility is being upgraded this year. The King Street (Freeport) facility is slated for replacement in several years from now, and is part of the current 10-year capital forecast with design anticipated to commence later this year. Further monitoring of the Old Mill facility will occur as a follow-up activity to the study to better characterize the situation at that facility, and is identified in the 10-year Capital forecast for improvements. The Bleams Road facility is a temporary one and will be decommissioned when the Middle Strasburg trunk sanitary sewer is constructed upstream to that point. Regarding the future growth scenarios, one facility is analyzed to be able to accommodate up to the 50% KGMS growth scenario but no more, six facilities to the 100% KGMS growth scenario, and nine facilities are expected to accommodate up to the full build out to current zoning scenario. The one facility (Patricia Ave) that can only accommodate up to the 50% KGMS growth scenario will require upgrades at some point to support such that level of growth, however the facility is relatively small and work that is not expected to occur in the near to mid- termfuture. ALIGNMENT WITH CITY OF KITCHENER STRATEGIC PLAN: This study has supported community priorities of: 1) Planned and sustainable development by ensuring the efficient and proactive provision of key services necessary for future development. 2) Environmental stewardship by ensuring that the City's wastewater system continues to operate in a safe and environmentally responsible manner. The study also supports the corporate foundation of efficient and effective government by providing an increased understanding of and ability to proactively plan and budget for a major class of critical City infrastructure assets. FINANCIAL IMPLICATIONS: There are no immediate new financial implications for the City as a result of this study over and above what is currently allocated in the 10-year capital forecast for sanitary sewer infrastructure. There are however 18 locations in the sewer network that were identified in the study requiring mitigation measures to address system capacity concerns. A class "C" cost estimate for all identified works was developed by the project consultant, with a total estimated cost of all works a 18-4 1 Staff Re ort p Krr~.~-~~,i~iER ~nfrastru~ture Servrces Department www.kitthenerta being $12.75 million. Much of this work is anticipated to occur over a span of time as the city grows though (perhaps 20 years, dependent on the rate of future urban growth), and includes the King Street East pumping station and catchment area which is currently in the 10-year Capital forecast and budgeted for. The value of newly identified work recommended for the near to mid-term commencement is estimated at $5.5 million. This work would be included into the ten-year capital forecast within the current forecasted funding envelope over the breadth of the forecast through reprioritizing proposed work. Other works identified to support the 50% up when growth in the city approached those estimated to occur 20+ years from now. to 100% KGMS growth scenarios would occur thresholds. These levels of development are See appendix "A" for a description of identified work and cost estimates. COMMUNITY ENGAGEMENT: This study being a strictly technical exercise, members of the public were not involved in this study. However all direct stakeholders within the corporation were actively involved in this project, including staff from INS-Engineering, INS-Operations, Community Services-Planning, and Finance and Corporate Services-Information Technology. Staff from all divisions listed provided input and participation in the project as direct participants andlor subject matter experts. CONCLUSION: Analysis of the results showed that in general the existing sanitary sewer system has sufficient capacity to accommodate flows up to the 100% KGMS anticipated growth scenario. 18 specific locations were identified where existing or future flows exceed current available capacity and the hydraulic model was used to evaluate proposed upgrades. These upgrades are proposed to be included into the 10-year capital forecast and in out-years beyond that, with timing based on demand from current and future population levels. Additional analysis should be performed as further growth and servicing information is known. The InfoSWMM hydraulic model created during this study is a living document which will be used by staff to assess the impact of future development and to evaluate sanitary sewer system upgrades. The model provides a accurate representation of the system as it existed when the model was built. In order to remain a useful planning tool into the future it is imperative that the model is updated regularly. Plans to do so are currently underway, or will be put into place later this year. ACKNOWLEDGED BY: Pauline Houston, Deputy CAO Infrastructure Services Department J 18-5 1 KITCx~i~~R Staff Report ~nfrastrurture Services Department ~w.k~~~~~r~erca ,~ ~ ~, s ~ ~S ~ °~ ~ ~ ~+ ~1 ~' ~ ~~ ~~ ~~ ~ w ~ ~ ~L ~~ ~ '~ ~~ . ~ ~ ~ ~. ~ . ~ ~aa,. 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