Transcript Document

Land Use Program
Septic System Overview
Scott Weldon
619 441 4086
[email protected]
Definition of “Septic System”
A subsurface sewage disposal system which uses a
combination of a septic tank and a effluent dispersal
mechanism.
 A two-chamber septic tank is used to accumulate solid
matter. The solid matter is decomposed by anaerobic
bacteria. Clear effluent then passes to the dispersal
mechanism, which may be leachlines or seepage pits.
 Septic tanks need to be pumped at least once every
four years to remove solids.

Septic Systems are required for
plumbed structures anywhere
there is no public sewer
 If public sewer is not within 200’ of a vacant
lot that is proposed to be built out, the owner will
need to install a septic system that is permitted
and inspected by the County of San Diego,
Department of Environmental Health.
 The intent of a properly designed septic system
is to keep sewage underground for at least 25
years.
Map of San Diego County
Percolation tests for septic systems
Percolation tests must be completed
to determine soil permeability.
 Consists of at least four 6” diameter borings
in the proposed leachline/ pit area.
 Must be completed by a licensed
professional, and must follow County Policy
for percolation test procedures.
 A deep boring is also required to verify
adequate soil depth and adequate separation
to groundwater . Deep borings are 15’-20’
deep.
Soil Permeability
 Soil must be able to accept water over time in
order for a septic system to work properly.
 Clay soils have poor percolation rates, and may
not support a septic system.
Groundwater Protection
requirements
5’ separation required from leachlines to groundwater.
 10’ separation required from Horizontal or Vertical Seepage Pits
to groundwater.
 100’ setback required from any portion of a septic system to a
water well.
 100’ setback required from a septic system to a year-around
stream
 50’ setback required from a septic system to a seasonal stream.
 ¼ mile setback required from a vertical seepage pit to any well

Permit Process
1.
2.
3.
A percolation test or septic layout is submitted
and is field reviewed by DEH staff. Project is
either approved or disapproved. If it’s
disapproved, the owner has 12 months to correct
any issues / concerns.
Grading must be completed prior to issuance of
the septic permit (i.e. pad or driveway grading).
A septic permit is then issued in order to install
the system. The permit is valid for one year, and
the system is inspected by the County at the time
of installation.
Types of dispersal mechanisms
 Leachlines – trenches 3’– 5’ deep with 1-2” rock
under and around 4” perforated pipe.
 Vertical Seepage Pits – 4’ diameter rock-filled
pits. The bottom of the pit is kept at least 10’
above groundwater. Vertical pits are only
allowed in areas with poor quality groundwater
(basically along the coastline where salt water
intrusion has occurred) .
 Horizontal Seepage Pits – A series of 5’ diameter
rings that are 6’ tall. Soil must be very
permeable (perc rate < 30 min per inch).
Surface discharge requirements
All sewage effluent is to remain underground. If a
septic system fails, the septic tank should be pumped
as necessary to keep sewage underground until repairs
can be made.
 A repair to a failing system usually consists of a 200’300’ leachline addition to the existing leachfield.
 County Code requires a failing system to be repaired
within 30 days.

Surface Discharge
Requirements (continued)
 Sediment control is important during the rainy
season.
 When excavating on your property, all runoff/sediment is to be kept on your property by
using sediment basins, berms and/or silt fences.
Reserve Requirement
 Each lot in San Diego County that has a septic
system on it must have a designated area to
replace the dispersal field should it fail. This
area is known as the “reserve area”. No
structures or hardscape may be placed in this
area.
 The average life expectancy of a septic system
is 25 years.
What can go into a septic tank?
 Domestic waste may go into a septic tank
 Industrial waste, solvents, pesticides or fertilizers
should not go into a septic tank.
 The introduction of toxic materials into a septic
tank will kill the biomat layer in the tank. The
biomat layer then breaks up and goes into the
leachline trenches, clogging the system up. This
leads to premature failure.
Farm Labor Housing
 Currently, there is no fee for the Department of
Environmental Health to review Farm Labor
Housing proposals.
 The lot must be able to support the additional
leachfield that will be required to accommodate
the laborers in order for the Farm Labor Housing
to be approved.
Future of Septic Systems in
San Diego County
State Assembly Bill 811
Promulgated by the State Water Board.
All Counties are to have standardized requirements for septic
systems.
“aerobic” septic tanks are to be the norm by 2007. Effluent
quality will be increased significantly, however the cost of
septic systems will triple ( from approximately $7,000 to
$25,000).
Separation requirement to groundwater will be reduced to 4’.
“Alternative” systems will be allowed.
All septic systems are to be certified annually that they’re
operating correctly by 2007(state Water Board requirement).
Alternative Systems
An “alternative” septic system consists of an aerobic
septic tank and a dispersal mechanism. (conventional
systems use anaerobic septic tanks).
 Oxygen is added to the aerobic tank by various
methods. The down-side to aerobic systems is that
they have moving parts and require electricity. This
opens the door to break-downs and/ or human error.
 The positive aspect is that effluent quality is
exponentially better.

Alternative Systems (continued)
Since effluent quality is better, it may be possible to
reduce the size of the dispersal field. Sizing of
alternative systems is in its inceptive stage, and is still
being worked out..
 4’ separation to groundwater will be required.

Example of a Septic Tank
Tank tied to leachfield
Example of a leachline