One of the Fraser Valley’s gems, Cultus Lake, is more than just a tourist attraction. The lake is of significant importance to Indigenous and non-Indigenous residents within the Cultus Lake community and the wider Fraser Valley. Each year more visitors (between 2-3 million) visitors come to enjoy the lake. This has placed pressure on the lake’s ecosystem, raising concerns about water quality and eutrophication.

In response, the Fraser Valley Regional District (FVRD) launched an extensive community engagement process and developed a liquid management plan that called for a modern wastewater treatment plant (WWTP) capable of producing Class A effluent, with additional phosphorus and nitrogen removal.

The WWTP boasts a comprehensive, multistage treatment process. The process starts at the headworks room, which consists of a grit vortex removal system, a mechanical screen, and a manual screen for redundancy. Influent then flows into one of two sequencing batch reactors (SBRs) for secondary treatment.

The SBRs produce two by-products:

1. Waste activated sludge, which is sent to aerated digesters. Sludge is stabilized in the digesters and is dewatered in the centrifuge. The dewatered solids are removed and transported for reuse as biosolids.

2. Secondary effluent is directed to the filtration building. The filtration building consists of two drum filters and two UV units. The drum filters help the effluent meet Class A requirements for TSS and turbidity, while UV disinfects the effluent before it is discharged into one of two rapid infiltration basins.

This facility also incorporates treatment for phosphorus and nitrogen removal. This project will provide treatment for nearly 5,400 people in its first phase, with the ability for expansion to serve a design population of nearly 14,300 people.

Given the project’s scale and complexity, an Integrated Project Delivery (IPD) model was chosen to bring the client, consultant, and contractor together under a shared commitment to project success.

To deliver the project successfully, the following steps were taken:

1. Early engagement with the contractor: engaging the contractor during the design phase helped save costs, as the contractor was able to identify design features that would be costly or difficult to construct. For example, the equalization tanks were originally designed to be underneath the filter building. However, the contractor noted a suspended slab would be much more expensive to build compared to having the tanks built outside.

2. Early procurement of equipment: To mitigate long equipment lead times, the client procured key components before design completion, preventing construction delays and keeping the project on schedule.

3. Collaboration, relationship building, and joint decision-making: On many large projects, owner–contractor–consultant relationships can become adversarial. Under the IPD model, shared incentives fostered trust and collaboration, prompting the FVRD to deliver the civil works in-house and realize significant cost savings.

The North Cultus WWTP was completed on budget and on schedule. It is providing Class A treatment and phosphorus and nitrogen removal to protect the health of Cultus Lake. Additionally, it is producing Class B biosolids from dewatered sludge, which are used for agricultural land application. The plant is currently in its first phase and has been designed to accommodate two future expansion phases, enabling service to additional areas such as Soowahlie First Nation and BC Parks.