Septic Tanks, Sewage Holding Tanks and Sewage Effluent Tanks

Table of Contents

1.

Scope

 6. Packaged Sewage Treatment Plants    Appendix A 
2.

Definitions

 7. Effluent Treatment and Disposal   Appendix B 
3.

General

 8. Treatment Mounds   List of Figures
4.

Piping

 9. Sand Filters     
5. Septic, Holding, and Effluent Tanks  10. Open Discharge System    
    11. Sewage or Effluent Lagoons     


Standard of Practice Explanation

5. Septic Tanks, Sewage Holding Tanks and Sewage Effluent Tanks

 See Pg. 166, Fig. Tanks 1 in Appendix "B"

5.1 Design Standards
5.1.1. A septic tank shall have a minimum working capacity of
  1. not less than 1800 litres (400 gal.),
  2. not less than the expected volume of sewage per day as prescribed in Table 3.1.14.A.,
  3. for a single family dwelling and duplex not less than
    1. 1800 litres (400 gal.) for a 3-bedroom home or less,
    2. 2700 litres (600 gal.) for a 4-bedroom,
    3. 3400 litres (750 gal.) for a 5-bedroom home, and
    4. 4000 litres (900 gal.) for a 6-bedroom home, and

  4. 2700 L (600 Gal.) but not less than 1.5 times the expected volume of sewage per day as prescribed in Table 3.1.14.A. if the septic tank supplies effluent to a treatment or disposal component that uses a pressure distribution lateral pipe system.

Note: Where additional biological loads, such as garbage grinders or fixtures that may increase sewage volumes, are included in the design of the facility served by the system, the size of the septic tank should be increased. If it is not increased in size, pump out and cleaning frequency will increase and the biological loading to the field will increase reducing the life of the treatment and disposal system

Note: Manufacturer's model number designation of their septic tanks do not necessarily indicate the "Working Capacity" of their products. For example a manufacturers model 750 is approximately 420 gallons working capacity. Therefore, caution must be exercised when sizing a septic tank.

Sizing requirements found in the Standard of Practice refer to the Working Capacity.

See Pg. 22, Article 3.1.14
See Pg. 44, Article 7A.1.9
See Pg. 166, Fig. Tanks 1 in Appendix "B"
See Pg. 167, Fig. Tanks 1a in Appendix "B" in Appendix "B"
See Pg. 102, To Select The Size of the Septic Tank in Appendix "B"

5.1.2. A holding tank shall have a storage capacity of not less than 1800 litres (400 gallons) or the expected volume of sewage per day as prescribed in Table 3.1.14.A., which ever is greater.

Intent: The capacity of the holding tank should be large enough to make effective use of trucking services and provide a reserve volume for the owner. In no case should the size of the tank be less than the volume of sewage per day. It is not the intent of this Standard to exclude the use of a septic tank as a holding tank providing the requirements of the Standard are met regarding holding tanks.

See Pg. 25, Article 3.2.1.

See Pg. 111, Sewage Holding Tanks in Appendix "B"

5.1.3. A holding tank, when used, shall be located and installed to accommodate the regular removal of sewage by vacuum truck or other approved means.

Intent: Holding tanks are meant to hold a volume of sewage and facilitate the removal of sewage for disposal in a municipal lagoon or other suitable location.

See Pg. 25, Article 3.2.1
See Pg. 111, Sewage Holding Tanks in Appendix "B"

5.1.4. Access openings and manhole extensions shall prevent water from entering a septic tank, sewage holding tank or sewage effluent tank.

Ground water entering the manholes is a common problem and overloads the septic tank and disposal and treatment system.

See Pg. 20, Article 3.1.4
See Pg. 21, Article 3.1.6
See Pg. 33, Article 5.2.4
See Pg. 101, Use of the Septic Tank in Appendix "B"
See Pg. 102, Location of the Septic Tank in Appendix "B"

5.2 Installation Standards

  
5.2.1. Septic tanks, sewage holding tanks or sewage effluent tanks shall not be located within
  1. 1 m (3.25 ft.) from a property line,
  2. 9 m (30 ft.) from a water source,
  3. 9 m (30 ft.) from a water course, and
  4. 1 m (3.25 ft.) from a building.

See Pg. 102, Location of the Septic Tank in Appendix "B"
See Pg. 169, Fig. Tanks 3 in Appendix "B"

5.2.2. A septic tank, sewage holding tank or sewage effluent tank shall be provided with an access opening that is not more than 600 mm (2 ft.) below the surface of the ground.

Intent: To facilitate cleaning of the tank by requiring a deep buried tank to include an access opening near the surface of the ground . Access requirements for maintenance of equipment must be considered when locating the access opening.

See Pg. 102, Location of the Septic Tank in Appendix "B"
See Pg. 110, Maintenance and Cleaning of the Septic Tank in Appendix "B"
See Pg. 169, Fig. Tanks 3 in Appendix "B"

5.2.3. Access openings that are not protected by their location shall be equipped with a secure lid or cover.

Intent: To increase safety by preventing unauthorized or accidental entry into the access opening of a septic tank or holding tank. Acceptable protective measures include but are not limited to:

  1. a padlock,
  2. a cover that can only be removed with tools, or
  3. a cover having a minimum weight of 29.5 kilograms (65 pounds).

The CAN/CSA B.66 Standard for Prefabricated Septic Tank and Sewage Holding Tanks encourages all manufacturers to provide a "Child resistant" access opening to prevent a child from accidentally falling into the septic or sewage holding tank.

Most concrete septic or sewage holding tank lids are heavy enough to be somewhat "Child resistant" provided they are replaced properly and cannot tip. Fibreglass and polyethylene tank lids are very light in weight and can be easily removed if the attaching screws etc. are not properly installed when replacing the lid on the septic or sewage holding tank.

5.2.4. An access opening extension shall be water tight at the connection to the septic tank, sewage holding tank or sewage effluent tank and at the joints between all sections.

See Pg. 20, Article 3.1.4.
See Pg. 21, Article 3.1.6.
See Pg. 32, Article 5.1.4
See Pg. 101, Use of the Septic Tank in Appendix "B"
See Pg. 102, Location of the Septic Tank in Appendix "B"

5.2.5. The bottom of an excavation for a septic tank, sewage holding tank or sewage effluent tank shall provide a uniform base to support the tank in a level position.

Intent: A tank must have a stable base so it will not settle, shift or crack after installation.

 See Pg. 105, Excavation For The Septic Tank or Sewage Holding Tanks in Appendix "B"

See Pg. 170, Fig. Tanks 4 in Appendix "B"

5.2.6. Piping connected to the septic tank, sewage holding tank or sewage effluent tank shall be supported to within 300 mm (1 ft.) of the tank on a solid base, or equivalent.

Intent: The inlet and outlet piping connected to a tank must be protected from distortion caused by settling of the backfill material. The excavation for a tank should not be any longer than is necessary to install the tank. This provides undisturbed earth closer to the tank to support the inlet and outlet piping connected to the tank. A pipe with a greater wall thickness provides an added factor of safety.

 See Pg. 170, Fig. Tanks 4 in Appendix "B"
See Pg. 164, Fig. Pipe 1 in Appendix "B"

5.3 Requirements for Materials

  
5.3.1. No person shall manufacture or install a septic tank, sewage holding tank or sewage effluent tank unless it
  1. meets or exceeds the requirements of CAN3-B66-M90 Standard and is certified by an accredited testing agency, or
  2. is subject to an engineering assessment acceptable to an Administrator and complies with a nationally recognized Standard or test requirements acceptable to an Administrator.

Certification to the B66 standard provides some assurance that the tank is built to an acceptable level of quality and provide the expected level of service when in operation.

See Pg. 101, Septic Tank in Appendix "B"