Standard Gravity Flow System
A system of narrow trenches partially filled with a bed of washed
gravel or crushed stone into which perforated or open joint pipe is
placed. The discharge from the septic tank gravity flows and is
distributed through these pipes into trenches and surrounding soil. The
subsurface absorption field must be properly sized and constructed to
meet the percolation rate of the surrounding soil.
Septic tank maintenance should include pumping the septic and
cleaning the effluent filter every three to five years. Because the
septic tank maintenance is critical to the over-all performance of the
sewage disposal system, failure to perform this maintenance can lead to
sedimentation and premature failure of the leach lines.
The primary and 100% repair area must be protected from vehicular
traffic, corrals, animal enclosures, stables, structures, below or above
ground pools, or any other activity that causes alterations such as
grading, cuts/fills, ect. Failure to do so may void any warranties.
Please note that all roof drainage should be diverted away from the
leach field. Irrigation in the area of the leach trenches should be kept
to a minimum to avoid saturating the soil. Drip irrigation should be
Also we recommend water conservation should be enlisted for household
water use to maximize the life expectancy of the absorption trenches.
Also take care of any household leaks immediately to avoid unnecessary
saturating of the leach trenches.
Below is a cross-section of a typical Standard System leach line.
Please note: this does not represent all standard system leach lines but
one type commonly installed in Nevada County.