Septic Components - Leach Lines
Leach lines are trenches that are filled with washed rock/gravel to flow level. Perforated pipe lays on top of the rock at a level grade. More rock is added to cover the pipe, and paper or other approved filter material is used to keep soil from filtering down into the rock. The paper does deteriorate, but by the time it does the soil is compacted enough to prevent it from dropping into the rock. Perforated leach lines are usually the first choice for a standard individual sewage disposal system design. The pipes of an approved material and are pre-drilled to allow the effluent to trickle through the gravel for treatment. The lines are also shallow enough (12" to grade) for some aerobic bacteria breakdown and some evapo-transpiration.
Cross-section of a leach line.
The area of an individual sewage disposal system's disposal field is sized based on the proposed sewage flow and the soil's percolation rate. Individual sewage disposal systems are designed to accommodate a sewage flow of 350 gallons per day plus 150 gallons for each additional bedroom. A standard leach line is considered to be three (3) feet wide and three (3) feet deep with a length as required. A non-standard leach line is wider, narrower, and/or deeper than three (3) feet with a length as required.
Gravel-less trench construction (e.g., Infiltrator® systems) may be utilized instead of drain rock in the disposal trench. The design, manufacturing, and materials used shall be durable and acceptable to the Department.
Installation of gravel-less leach line chambers.