Snaw-naw-as Sanitary Sewer System (Snaw-naw-as land near Nanoose Bay, BC)

The Snaw-naw-as (Nanoose First Nation) had a major problem. The majority of thee individual onsite septic system tile fields were failing. The raw sewage was breaking out of the ground and flowing to areas where children played, which caused a major health problem for the community.

This was also a serious environmental problem as their sewer ran through the ditches and creeks in their village to the foreshore of Nanoose Bay.

And it posed a cultural and economic problem because the beaches were contaminated and the traditional harvesting of clams on the beach was prohibited for health reasons.

Chatwin Engineering provided the solution by designing and building a state of the art sanitary sewer collection system, major sewer pumping station, sanitary sewer treatment facility, and a 2.2km outfall.

Our first challenge was the justification of our planned location of the treatment facility. The approval authorities wanted it located on the waterfront, like most of the treatment facilities for municipalities. We wanted to locate it across the highway, in a remote portion of the reserve, approximately 1km away from the ocean. Our rationale was that we didn’t want to compromise the future development of the waterfront property and we wanted it downwind and remote to minimize odour concerns.

We ran a comparison model for life cycle costing of the two locations and were able to convince the funding authorities by including the value of the land for the locations as part of our analysis.

The next challenge we encountered was public concern about pollution in Nanoose Bay from the effluent outfall. The quality of the sanitary sewer from the nearest Regional District of Nanaimo Sanitary Sewer Outfall was BOD<45 and TSS<45. We promised to deliver a BOD<10 and TSS<10. After the project was complete the monitoring showed consistent results of BOD<5 and TSS<5, far exceeding the requirements and satisfying the concerns of the community.

People’s concerns about odour were addressed with a multi-barrier approach: locating the plant downwind of development, selecting a treatment process that had minimum odour, and totally enclosing the facility in a building and running the air through a scrubber to eliminate odour. Since the plant was built, there have been no odour complaints.

Today the sanitary sewer system at Snaw-naw-as is working flawless, producing the highest quality effluent on the coast. The children of the village play in a safe and healthy environment and the people of Snaw-naw-as once again enjoy the commercial shellfish harvest from their beaches.

An added environmental bonus for this community

We were required to construct the outfall line along the beach, which was suffering from severe erosion caused by retaining walls on adjacent ocean properties. To protect the foreshore we developed one of the first Greenshore Projects in British Columbia. We replaced the existing riprap that damaged sensitive inter-tidal habitats with a gravity sloping beach filled with round rocks that gently rolled up and down the beach dissipating the energy of the waves. See how our Environmental Division (link) contributed to this project.

Download the technical specifications for this project. (3.2MB)