Designing Your OnSite Wastewater Treatment System

Owner's Manual available for purchase from WCOWMA BC.

Planning on a new onsite wastewater treatment system for your property? This owner's manual will help to get you started.

The design of an efficient and cost-effective onsite wastewater treatment system (OWTS) ensures performance, longevity, and protection of the environment. The design of the system for your property requires site visits, soil testing, assessment of building occupancy and use, and the creation of a site plan. This investment in site assessment and design is the most valuable expenditure you can make.

In planning your system, a Planner/Designer will:

1. Make a site drawing of your property and evaluate the area available for a wastewater system. It may be necessary to alter the landscaping and natural elements of your property at the system location.

2. In the site drawing, the planner/designer will show the location of other utilities including your well and the location of any public water adjacent to your property.

3. The planner/designer will evaluate the soil conditions of your property to determine its ability to accept and treat wastewater. The soil texture will be assessed in the field and confirmed with a laboratory analysis. In some jurisdictions either a percolation test or a permeameter test may be performed at the treatment site to confirm the effluent hydraulic loading rate. The quality of the domestic water supply will also be considered since sodium, iron and other components of well water are a factor in system design.

4. The planner/designer will ask you to supply information on the size and use of the structure in existence or to be built. In the case of a residence, the area of the structure, the number of bedrooms and the expected occupancy will be a factor in design. If the home has high volume water use appliances, will be used for high water use activities, and/ or will be used for a home-based business, the capacity to accept the additional wastewater will be designed into the system.

5. The planner/designer will establish a peak daily flow rate expressed in gallons or litres per day the system must be able to handle. The flow rate must meet or exceed the minimum standard specified by the provincial regulatory framework.

   
   

After completing the tasks above, the planner/designer will recommend one or more systems suitable for your property based on the flow rate, the land area available, the site and soil conditions and the presence of adjacent public water.

A system design that meets or exceeds the requirements of the provincial regulations must be submitted to the authority having jurisdiction in order to obtain either a permit from the permitting authority prior to construction or acceptance of the filing by the health authority.

Once the system design paperwork has been submitted to the appropriate body and accepted, then the installation may begin. In most jurisdictions an inspection of the system is required prior to completion. In the absence of a requirement for final inspection as-built drawings and a Letter of Certification from the installer will be required.

There are five types of systems commonly in use in Western Canada. They are:

• Septic tank and soil treatment component such as a treatment field

• septic tank and a sand treatment mound

• Advanced treatment unit and soil treatment component

• Open Discharge (also called Ejector systems) (not permitted in BC)

• Advanced treatment unit and at-grade soil treatment component

This information is from the Western Canada On-Site Wastewater Management Association (WCOWMA). To purchase a detailed Private OnSite Wastewater Treatment System Owner's Manual - A guide to the use and care of your private facility click this link https://wcowma-bc.com/product/wcowma-homeowner-manuals/