Wastewater Treatment Plant Expansion and Improvements


A new secondary clarifier and concentric ring bioreactor is being built. This major upgrade will increase treatment capacity, provide system redundancy, increase seismic and flood resiliency, improve plant performance and effluent quality, decrease biosolids production and associated energy usage, and decrease carbon emissions and handling costs. 


The Squamish Wastewater Treatment Plant is reaching full capacity and requires upgrades to meet population growth forecasts and redundancy requirements in accordance with the Municipal Wastewater Regulations. This refers to the need for 75% biological treatment capacity with the largest unit out of service. Currently the plant has 55% redundancy which would be reduced further based on projected future flows.

The existing treatment units are approaching end of life and and do not meet current seismic and flood protection design considerations. The new post-disaster infrastructure will be able to withstand seismic and flood events, which is of critical importance in light of recent catastrophic flooding events across British Columbia. 

Project Information

The scope of work includes:

  • Construction of new secondary clarifier and concentric ring bioreactor.
  • Conversion of an old clarifier tank into a primary clarifier (optimize existing infrastructure and create ongoing value from old infrastructure throughout its remaining useful life).
  • New septage receiving station (septic systems from Squamish and recreational sites along the Sea to Sky corridor will benefit from the improved septic receiving station).
  • Electrical and control system upgrades.
Project Schedule

Construction is anticipated to take place through summer 2025.

Project Funding

The total project cost is estimated at $20.2M. The project is funded by Developer Cost Charges and grants. $8,080,808 of this project is proposed to be financed by debt to spread the cost of the project out over time, ensuring that future taxpayers also support the upgrade. The annual utility bill impact represents approximately $5.00 per residential property.

A budget amendment was presented to Council on April 18, 2023, due to cost escalation related the project’s Request for Proposals (RFP) bids being significantly higher than anticipated when the financial plan (FP) was originally drafted. Read the Report to Council

Cost escalation factors: 

General cost escalation due to post-Covid pressures: 

  1. Supply chain issues, delays and shortages.
  2. Increased materials cost.
  3. Increased labour costs.

Project-specific cost escalation: 

  1. Ground improvement for improved seismic resiliency. Deep soil mixing was chosen due to tight space constraints and proximity to nearby infrastructure. Low vibration method, that reduced risk of settlement to existing infrastructure. Higher cost than alternative methods (stone columns, compaction piles). Cost $2.2M.
  2. BC cement shortages last summer due to supply chain issues and exacerbated by Lafarge plant fire. Further Increased costs for deep soil mixing which required a large volume of cement; and
  3. Contaminated soils were encountered onsite. Unknown condition at the time of budgeting. Expensive to delineate, remove and dispose of. 
Site Plan and Clarifier Design

Site Plan:

Site plan

New Clarifier Design

New clarifier drawing.

Environmental benefits
  • The District currently produces 45,000kg of CO2 emissions annually from trucking biosolids to the Callaghan Composting Facility. This project will reduce biosolids production by approximately 10% resulting in a considerable reduction in CO2 emissions.
  • This upgrade will reduce aeration requirements in the treatment process resulting in a 35% reduction in electricity consumption for aeration helping the District to achieve its municipal energy and emissions reduction targets.

Previous Updates
November 2022
  1. Deconstruction of existing storage sheds was completed in May 2022 - 95% landfill diversion was achieved by salvaging useful materials, source separation, recycling of materials, and relocation of intact buildings off-site for continued use.
  2. Environmental and Archeological Permits obtained May 2022 - Due to the nature of the activities at the WWTP site, significant contamination drilling, testing, mapping and reporting were required before any excavation activities could commence. This was required to determine and delineate any potential contamination and provide recommended rehabilitation. Due to the location of the site and the higher archeological potential, numerous archeological test digs, reporting and consultation with First Nations assessed the site before any excavation activities commenced.
  3. Relocation of impacted utilities and mass excavation under the proposed new circular treatment tank was completed in September 2022 - All impacted utilities were decommissioned and/or rerouted around the circular excavation. This included the installation of 100m of 900mm storm main. All contaminated soil was removed and disposed of following strict environmental regulations and practices. To reduce offsite removal and trucking costs, excavated materials were repurposed for Public Works facility preload.
  4. Ground improvements were completed in October 2022 - Deep soil mixing was implemented to densify the ground under the proposed circular tank to prevent ground liquefaction during an earthquake and increase seismic resistance. This was required as this infrastructure is designed to be a post-disaster structure.  Low-strength concrete panels were drilled to a depth of 13m. An onsite concrete batch plant was constructed to reduce concrete truck traffic and ensure consistency in product and delivery. 
  5. Detailed Design and Tendering for the next phase completed in September 2022 - Eight contractor proposals were received and reviewed.

Next Steps: Contract award for the next phase of construction

We are currently interviewing contractors for the next phase of construction. Next phase of work includes; tank construction, piping, septage receiving station, rehabilitation and reuse of some existing tanks. The anticipated contract award is December 2022 with construction expected to start back up in early Jan 2023. Timeline for project completion is Q1 2024.

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