Septic System Installation
Private septic systems are required for residential, commercial and industrial buildings that are not connected to municipal or public waste water systems/treatment plants. The private systems function to receive and treat waste water (from toilets, showers, sinks, dishwashers, washing machines etc.) and return the treated effluent into the groundwater system.
A conventional septic system is composed of a septic tank and a soil filter called a leaching bed or drain field. There are two traditional types of septic systems, as explained below:
Septic Tank Systems
A septic tank system consists of an underground container or tank for receiving, treating, and settling wastewater. The solids settle to the bottom of the tank and become sludge, while the oil and other light materials float to the surface forming a scum layer.
Anaerobic bacteria (bacteria that do not need oxygen) are placed in the tank to break down the solid waste. Within a fully functional septic tank, the bacteria are expected to reduce the solids by 50-60%. The liquid between the sludge on the bottom of the tank and the scum on the top flows out of the tank into the disperal area, where further treatment occurs within the soild, until the liquid effluent is harmless and inert. The sludge and surface oils which remain in the septic tank are pumped out regularly. This serivce is provided by septic cleaning companies.
Treatment Plant Systems
A typical treament plant system uses air (oxygen) to help break down and treat the wastewater. In some cases, the wastewater is treated in a septic tank before flowing into the treatment plant. A treatment plant treats liquid wastewater to a higher quality than a septic tanks system, making the effluent cleaner and safer before it is discharged into the dispersal area.
Standards and Regulations
The Municipal Sewage Regulation which applies to daily sewage flows of 22,700 or more litres per day and the new Sewerage System Regulation (2005), which applies to sewage flows of less than 22,700 litres per day, together regulate wastewater disposal and related systems in BC. Under the Sewerage System Regulation (SSR), septic systems are now categorized according to three performance standards or levels. These standards relate to the type of treatment system required and the quality of the effluent that is discharged. The three levels are as follows:
| Type One | treatment by septic tank only |
| Type Two | treatment that produces an effluent consistently containing less than 45mgl of total suspended solids (TSS) and having a 5 day biochemical oxygen demand (BOD) of less than 45mg/L. Mainly for sites that require secondary treatment. |
| Type Three | treatment that produces an effluent consistenly containing less than 10 mg/L of total suspended solids and having: |
| (i) a 5 day biochemical oxygen demand of less than 10 mg/L, and | |
| (ii) a median fecal coliform density of less than 400 colony forming units per 100. |
