Ontario Building Code: Septic Stone and Leaching Chamber Installation Standards
Sarah's Expert Insight
OBC Compliance Specialist
"At empcontracting.ca Inc., your construction contractor in London, Ontario, we emphasize that strict adherence to stone gradation and self-draining pipe requirements is vital for preventing system failure in the heavy clay soils of London or the rocky terrains of Muskoka. Ensuring pressurized pipes are properly pitched to be self-draining is a non-negotiable step to prevent winter freeze-ups and costly repairs in Southern Ontario’s harsh climate."
Section 8.7.3.4: Septic Stone Layer and Pressurized Pipe Requirements
Proper installation of the septic stone layer is critical for the longevity of a leaching bed. According to the 2024 Ontario Building Code, the stone layer must be protected prior to backfilling to prevent soil or leaching bed fill from contaminating the stone. This is achieved by completely covering it with untreated building paper or a permeable geo-textile fabric.
Pressurized Distribution Pipe Specifications
For systems utilizing pressurized distribution, the following standards apply:
- Self-Draining: Every pressurized pipe must be self-draining to prevent freezing.
- Sizing: Pipes must be at least 1 inch trade size.
- Orifices: Openings must be at least 3 mm in diameter and spaced equally for even effluent distribution.
Stone Quality and Gradation
The stone used must be washed septic stone, free of fine material. As per Table 8.7.3.4, the stone must meet specific gradation requirements (100% passing 53 mm, and only 0-5% passing 19 mm). The stone layer must be at least 500 mm wide, extending 150 mm below the pipe and 50 mm above it.
Section 8.7.3.5: Leaching Chamber Installation Standards
Leaching chambers provide an alternative to traditional stone and pipe systems. When installing these units, compliance with the following is mandatory:
Installation and Integrity
- Leveling: Chambers must be installed level over the entire length of the trench.
- Connection: Sections must be securely connected and free of structural damage.
- Protection: End caps and splash plates (at the inlet) are required to prevent soil scouring and entry into the chamber.
Distribution Pipes within Chambers
For dosed or pressurized systems within a leaching chamber, the trade size requirements increase. Distribution pipes for dosed systems must be at least 3 inches, while pressurized pipes must be at least 1.5 inches with 6 mm orifices. Crucially, these systems must include cleanouts at the downstream end to allow for ongoing maintenance and servicing.
For professional implementation of these standards, contact empcontracting.ca Inc. your construction contractor in London, Ontario.
Disclaimer: This content is generated from the Ontario Building Code for educational purposes. Always consult with a licensed professional engineer or your local building department before starting any construction project in London, Ontario.