TAMRMS#: B06
5.2
Information Item Only
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Northeast Servicing Update
Presented by: Jordan Betteridge, Manager Asset Management, Land, Integrated Infrastructure Service, Engineering Services
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SUMMARY
This report provides an update regarding a developer submitted proposal to utilize existing deep sanitary trunks for pipe storage, which would create additional interim capacity in the sanitary system allowing additional stages of development to occur in the Jensen Lakes and Erin Ridge North areas until the ultimate Northeast Servicing Project is commissioned. An update to the ultimate Northeast Servicing Project funding will be provided through a recommended in-camera component to provide confidential information and progress regarding Administration’s work with third parties on a substantive funding model for the ultimate Northeast Servicing Project.
ALIGNMENT TO COUNCIL DIRECTION OR MANDATORY STATUTORY PROVISION
N/A
BACKGROUND AND DISCUSSION
Development within the northeast part of the City (e.g. Jensen Lakes and Erin Ridge North) is expected to utilize all of the existing sanitary capacity for the area. To address the long-term servicing needs for these development areas, the City has been working towards the ultimate Northeast Servicing Project which would entail construction of new utility infrastructure which would create additional capacity in the system that is needed to support the long-term growth in the North and Northeast. In advance of this ultimate Northeast Servicing Project, the developers have requested the City evaluate an interim solution that could provide limited additional sanitary capacity to support additional stages of development in the near term.
Interim Pipe Storage Concept:
In late 2024, two developers submitted proposals for the City to consider an interim sanitary solution. The proposed approach utilizes an existing deep sanitary trunk system to temporarily store peak sanitary and wet weather flows during wet weather events. The flows would be released at a controlled rate which would not exceed the downstream system’s capacity. The proposal would utilize the existing 1200mm diameter deep trunk system along Everitt Drive, to attenuate the flows into the Oakmont 450mm diameter sub trunk system (Attachment 1).
Initial review of the proposal was found to have merit, as it conceptually aligns with the ultimate design plan for the Northeast Servicing Project. Under the ultimate Northeast Servicing design, limitations had been placed on the release from the planned northeast lift station based on Arrow Utilities’ receiving capacity. Therefore, the ultimate design already had to incorporate storage of wet weather events within this pipe system, thereby reducing the Northeast Lift Station ultimate wet well capacity for storage and directly reducing the capital cost of investment in the lift station. While there were a few differences between the developer’s interim proposal and the ultimate design, the City’s cross-functional team undertook a comprehensive review to assess feasibility, identify risks, and determine appropriate measures.
The City reviewed the proposal through an engineering and operational lens on criteria such as performance, lifecycle impacts, financial considerations, maintenance and operations requirements, and public risk. Specific technical items relevant to this system included backup risks, odour, corrosion, and maintenance.
The primary concern for the pipe storage system is the introduction of the risk of sewer backups from high flow, specifically residential services connecting to the trunk pipe. Through this proposal, the City required specific safeguards to protect both upstream and downstream customers from the risks of unexpected backups. The safeguards include an overflow weir at the control manhole together with real-time flow and level monitoring devices to alert Utilities Operations of any issues. In the event of high flow occurrence, additional internal operational measures will be implemented as parallel requirements to help mitigate the risk of sewer back up to service lines.
Potential incremental odour risks will be managed through proactively monitoring the system through the installation of hydrogen sulfide (H2S) monitoring devices. While retention does increase odour potential, it is noted that the cause of odours depends on the concentration of the wastewater, the retention time, and the air ventilation. Since the primary retention periods occur during wet weather events which will then be diluted from the groundwater and stormwater that infiltrate and inflow (I/I) into the sanitary system, the concentration of the retained wastewater would be significantly diluted. In addition to regular flushing of the system, passive air circulation has been included in the design, and therefore it’s expected to be of low risk from odours. In the event of unexpected impacts, the City would implement a contingency of odour controlling measures that can be utilized.
To minimize any corrosion potential of the sanitary system, the design recommends lining of any pipe system and manholes susceptible to corrosion and thereby reducing the impact to the life expectancy of these existing assets. In addition to the engineered safeguards considered as part of the design, there are multiple administrative measures considered from an operations and maintenance perspective, which in tandem is expected to mitigate all potential risks to the system and ultimately to the City.
Since the infrastructure required for this project would ultimately become a component of the ultimate offsite Northeast Servicing Project (Sanitary Levy Project 2), the costs of this project are leviable. It is expected that the developers will front-end the full costs of design and construction of this interim solution. The additional maintenance and operational requirements from this proposal are expected to be paid by developers for an agreed upon period of years or until the ultimate Northeast Servicing Project is commissioned, whichever comes first. The maintenance and operational charges would not be leviable costs and would become City’s cost after the developer’s period of payment expires.
As a final condition for the developers, the City would require them to construct their permanent lift stations with their next stages of development (Attachment 2). This provides the City an option to revert the system if the field data varies significantly from the technical forecasts and assumptions presented in the design. The permanent lift stations would provide capabilities to provide storage within the wet wells and utilize advanced Supervisory Control and Data Acquisition (SCADA) information to offset the pumping during off-peak hours. This is the City’s backstop option with this proposal.
It should be noted that City Administration has also determined that the interim lift stations currently in place for both developers no longer provide the operability and reliability needed for accommodating further development and the permanent lift stations would be conditions of their next stages of development.
Based on the design reports, it is expected that this proposal could provide 7.7L/s of sanitary capacity, representing approximately 700 medium-density residential lots. The City would retain full authority and unfettered discretion over the allocation of any newly created capacity, and it would be planned to be released in phases, allowing the City to monitor the field data and system performance to ensure it matches the analysis and forecasts within the design reports.
To ensure the infrastructure is constructed prior to new development being approved, a Tri-party Agreement between the City and two active developers would be required to lay out all terms, conditions, and responsibilities to design, fund, and construct the interim system as well as items related to ongoing operation and maintenance. Execution of the Tri-party Agreement is required prior to any approvals of new development subdivisions. The agreement also includes the expected completion of construction of this interim system to be within six months from signing of the agreement, which would potentially enable the developers to submit new applications of subdivision and construction to proceed within the 2025 construction season.
Lastly, it should be noted that although the City is supporting this proposal on a case-specific basis, it is not to be interpreted as a new servicing standard. Administration would continue to treat any non-typical proposals as a variance requiring detailed analysis based on the specific site context to ensure it is acceptable to the City from the performance, cost, and risk parameters.
Next Steps:
Should either Landrex or Melcor still wish to proceed with the Interim Pipe Storage Concept, Administration will continue to coordinate with the developers on the finalization of the Design Basis Report and the Tri-party Agreement, which would then lead to approval of subdivisions within the noted servicing areas to enable development as early as 2025 with the expectation that the detailed design and construction of the interim solution will be completed and commissioned prior to any endorsement of subdivisions.
Northeast Servicing Project Funding
Since the last Council update on November 5, 2024, City Administration has been working on finding a substantive funding model with third party funding sources for this project.
It is recommended that Standing Committee of the Whole move in-camera to discuss confidential financial matters related to the Northeast Servicing Project and the following motion could be adopted for consideration:
“That Standing Committee of the Whole move in camera in accordance with sections 24(1)(a),(c),(g) of the Freedom of Information and Protection of Privacy Act.”
The legal basis for moving in camera are sections 24(1)(a), 24(1)(c), and 24(1)(g) of the Freedom of Information and Protection of Privacy Act, which allow the City to keep confidential advice, recommendations, and policy options, as well as positions and criteria for the purpose of negotiations that, if disclosed, could reasonably be expected to reveal information, including the proposed plans, policies or projects of a public body, the disclosure of which could reasonably be expected to result in disclosure of a pending policy or budgetary decision.
STAKEHOLDER COMMUNICATIONS OR ENGAGEMENT
Administration worked collaboratively with active developers and their consultants during the concept phase and design basis report for this interim pipe storage option.
ALIGNMENT TO PRIORITIES IN COUNCIL’S STRATEGIC PLAN
Initiative aligned with Strategic Plan:
None at this time
ALIGNMENT TO LEVELS OF SERVICE DELIVERY
D. Land Use and Development
D.2 Infrastructure Planning
D.2.1 Off-Site Levy Program
Support growth and development by administering City's off-site levy program for essential infrastructure needed.
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Report Date: June 10, 2025
Author(s): Jordan Betteridge, Manager AMLIIS
Department: Engineering Services
Department Director: Dawny George
Managing Director: Adryan Slaght
Chief Administrative Officer: Bill Fletcher