Sechelt Water Resource Centre | Implementing an Innovative Water Reuse Facility in British Columbia

Providing owner’s engineer services throughout the design-build implementation of an innovative water reuse facility in British Columbia
Nov 3, 2017 6:00 AM ET

Leading with Science

Tetra Tech provided owner’s engineer services for a cutting-edge water reuse plant in British Columbia that serves as a model for sustainable, innovative, and cost-effective wastewater treatment in small communities.

In response to higher demand from its growing population, the District of Sechelt in British Columbia needed to replace two aging wastewater treatment plants to meet capacity and effluent quality demands. The existing plants failed to effectively handle residuals and had significant noise and odor issues. The District of Sechelt also faced a significant investment to replace its aging outfall. Instead of refurbishing both plants, the District elected to build a single, new plant that would go beyond simply meeting regulatory requirements to provide a sustainable, LEED Gold-targeted facility with capacity for expansion. The community envisioned a plant that met indirect reuse water quality standards; maximized social, environmental, and financial value; limited noise and odor; and included sustainable features to maximize resource recovery. The District of Sechelt selected Tetra Tech to provide owner’s engineer services throughout project execution.

As owner’s engineer, Tetra Tech provided pre-design document reviews; developed design-build request for proposal (RFP) documents; assisted in managing the procurement process and execution; and provided design development support, construction administration, and commissioning support. Our team created a comprehensive operations and maintenance reporting spreadsheet that captured all anticipated costs to the community. The selected design-build team was contractually required to meet the guaranteed performance throughout the entire project, documenting it through the Tetra Tech-created spreadsheet, to ensure the new plant met the community’s goals.

The community mandated that the plant provide the highest level of treatment and serve as a template for other small communities. The community’s sustainability plan set project goals including supporting future growth and fully integrating resource recovery such as offsetting potable water use and eliminating regular use of the aging ocean outfall.

Our team managed the shutdown of the more inefficient of the two existing plants within an ambitious 18-month timeframe. Following commissioning of the new plant, the second plant was shut down.

The Sechelt Water Resource Centre is the first in North America to use the Organica Fed Batch Reactor process to achieve exceptional water quality with a small footprint that includes allowance for future expansion.

The process design includes plants suspended over treatment tanks enclosed in a greenhouse. The plant roots enhance the biological treatment process, making it more efficient, reducing energy and space requirements. The greenhouse also helps meet the aesthetic objectives for building the facility in a residential area, as well as controlling fugitive odors and noise. The completed plant meets the community’s 1 odor unit criteria (i.e. no detectible odors with a sample diluted 1 time) and complies with the community’s existing noise bylaws (under 55 dBa, a measure of the relative loudness of sound, in daytime and 45 dBa at night), even when standby generators are operating. Although the plant was created with a small footprint, the plans allow for future expansion.  

The wastewater treatment plant is part of the fabric of the community, with the system disguised as a greenhouse and botanical garden between residential areas and the Sechelt Marsh nature reserve. The site surrounding the plant is slated to be transformed into a public park where residents are free to observe the bioreactors. The building includes a public meeting room that supports educational tours and community events.

Upon commissioning, the plant achieved biochemical oxygen demand (BOD) less than 2, total suspended solids (TSS) less than 1, and no detectible fecal coliforms. This plant is in the top tier of treated water quality compared to similarly sized plants throughout Canada. The effluent is in full compliance with Canada’s new ammonia criteria that will come into effect in 2020. The efficient treatment process also removed the need for expansion of the current outfall, saving the District a one-time $3 million investment, and allowing it to be used only for emergencies.

The plant design also effectively limits operational costs, which was an important consideration in selecting the treatment technology. While meeting indirect recycling water quality and Class A biosolids standards, the plant operates using roughly 40 percent less electrical energy than the previous two plants. The building and process are pending LEED Gold certification.

The project also met the community’s goal of a facility capable of providing enhanced public education regarding water reuse and a demonstration platform for the use of innovative approaches and technologies.

The Sechelt Water Resource Centre exceeds the treatment capacity of the two previous wastewater treatment plants while meeting reuse quality standards. This facility has created an opportunity to transform how wastewater treatment is viewed in Sechelt and beyond.