PEO registered Engineers
Qualified designers by OBC
Civil & Municipal Engineering Consulting Company
Specialized in Septic Systems Design
Site Plans & Lot Grading
Municipality & Conservation Authority
What is a septic system?
A septic system is a highly efficient, self-contained,
underground wastewater treatment system. Because
septic systems treat and dispose of household
wastewater onsite, they are often more economical
than centralized sewer systems in rural areas
where lot sizes are larger and houses are
spaced widely apart.
Septic systems are also simple in design,
which make them generally less expensive
to install and maintain. And by using natural
processes to treat the wastewater onsite,
usually in a homeowner's backyard, septic
systems don't require the installation of
miles of sewer lines, making them less disruptive
to the environment.
|reference from Maryland University web
A septic system consists of two main; a
septic tank and a drainfield. The septic
tank is a watertight box, usually made of
concrete or fiberglass, with an inlet and
outlet pipe. Wastewater flows from the home
to the septic tank through the sewer pipe.
The septic tank treats the wastewater naturally
by holding it in the tank long enough for
solids and liquids to separate. The wastewater
forms three layers inside the tank. Solids
lighter than water (such as greases and
oils) float to the top forming a layer of
scum. Solids heavier than water settle at
the bottom of the tank forming a layer of
sludge. This leaves a middle layer of partially
The layers of sludge and scum remain in
the septic tank where bacteria found naturally
in the wastewater work to break the solids
down. The sludge and scum that cannot be
broken down are retained in the tank until
the tank is pumped.
The layer of clarified liquid flows from
the septic tank to the drainfield or to
a distribution device, which helps to uniformly
distribute the wastewater in the drainfield.
A standard drainfield (also known as a leaching
field, disposal field, or a soil absorption
system) is a series of trenches or a bed
lined with gravel or course sand and buried
one to three feet below the ground surface.
Perforated pipes or drain tiles run through
the trenches to distribute the wastewater.
The drainfield treats the wastewater by
allowing it to slowly trickle from the pipes
out into the gravel and down through the
soil. The gravel and soil act as biological
Classification of Septic Systems proved by
BMEC & OBC
In 1998, septic systems regulations were
put into the "Building Code of Ontario(OBC)
which is administered by local municipalities.
You need prior approval from your local
municipality before you can undertake
any septic system construction.
Septic System using Tertiary Treatment:
Filter Bed: a filter, installed at the
outlet of septic tank. This filter dramatically
improves the quality of effluent discharged
to the leaching bed.
Septic systems:The chambered system is
a replacement for the conventional stone
and pipe leaching bed. The chambers containing
the distribution pipes are installed in
0.5 - 0.9 metre wide trenches. The pipes
are not pressurized. Approximately the
same length of trench is used as with
the pipe system, only there is no crushed
Engineering services for a septic system
engineering services for on-site sewage
systems include the following:
topographic survey and subsurface soil
investigation of property
laboratory analyses of soil samples to
assess percolation rates (Unified Soil
of detailed AutoCAD design drawings (includes
site & grading plan, septic systems
details, septic specifications & notes)
completion of a permit application for
Municipalities (i.e. Town or City)
inspections at the time of construction
to certify installation
In addition to preparing
detailed on-site sewage system designs,
Gunnell Engineering Ltd. provides the following
& evaluations of existing sewage systems
of the use of a tertiary treatment system
in place of a conventional septic tank
to provide subsurface conditions &
laboratory analyses of delivered soil
samples to provide an estimated range
of percolation rates (‘T’
Tips for Using Your Septic System
Make efforts to minimize the amount of
water that goes into the onsite sewage system;
typical water use is about 227 liters (50
gallons) per day for each person. Try not
to exceed that amount. Having a water meter
installed will help you monitor your water
Systems are designed to handle domestic
wastewater. Things that do not break down
easily (facial tissue, large amounts of vegetable
scrapings, coffee grounds, chemicals, paints,
oils, sanitary napkins, applicators, condoms,
medicines, pesticides, poisons, strong disinfectants,
etc.) can damage a system or substantially
increase the need for cleaning the septic
Restrict the use of in-sink garbage disposals.
They add a large amount of organic and inorganic
material to your sewage, which may exceed
your system's capacity and cause it to fail.
Do not pour grease or cooking oil down the
drain (including toilet). Grease and oil
is hard to break down. It will eventually
move into the soil, plugging it off.
Keep your fixtures in good repair. A slow-running
toilet can add large amounts of water.
A running toilet discharging ¼ gallon
per minute will result in 360 gallons per
day. This is more water than a sewage system
for a 3-bedroom home is designed for. To
test the toilet, put a few drops of food
colouring in the toilet tank. If it shows
up in the bowl, it is leaking. It may take
as long as an hour for colour to show in
Tips for Maintaining Your Onsite
Wastewaters not included in the system's
design should not be put into the system.
This may include wastewater from:
- foundation weeping tile drains,
- a hot tub, spa or hydro massage bath exceeding
a 2-person capacity,
- a swimming pool,
- an iron filter,
- water conditioning equipment that generates
excessive amounts of wastewater.
a diagram showing the location of your septic
tank and disposal field.
not already in place, install watertight
manhole extensions to simplify septic tank
Make sure the access lids are structurally
sound, secure and childproof.
access lids are buried, consider raising
them above grade to facilitate access.
the septic tank checked annually to determine
how often the tank needs to be pumped out.
(typically tanks are pumped out by a vacuum
truck approximately every two years)
pumps are used in the system, have any pump
screens cleaned (make sure they are re-installed)
and have the control operations checked.
adequate vegetative cover over the disposal
field. Keep the grass trimmed.
eavestrough downspouts, and other surface
water flows away from the septic tank and
are installed near the surface - keep automobiles
and heavy equipment off the system. The
piping and septic tanks can be damaged by
heavy traffic, and the traffic will compact
the ground reducing its ability to absorb
sewage effluent. In winter, traffic (even
from snowmobile paths) will drive frost
into the system causing it to freeze.
AND FEEDING OF YOUR SEPTIC TANK
ROGER E. MACHMEIER, Ph.D., P.E.
PROFESSOR EMERITUS, UNIVERSITY OF MINNESOTA
the septic tank is such an essential part
of a sewage system, here are some points
to remember about the "care and feeding"
of that part of the onsite sewage treatment
A "starter" is not needed for
bacterial action to begin in a septic
tank. Many bacteria are present in the
materials deposited into the tank and
will thrive under the growth conditions
you feel that an additive is needed, be
aware that some may do great harm. Additives
that advertise to "eliminate"
tank cleaning may cause the sludge layer
to fluff up and be washed out into the
drainfield, plugging soil pores. Some
additives, particularly degreasers, may
contain carcinogens (cancer-causing) or
suspected carcinogens that will flow into
the ground water along with the water
from the soil treatment unit.
all sewage into the septic tank. Don't
run laundry wastes directly into the drainfield,
since soap or detergent scum will plug
the soil pores, causing failure.
Normal amounts of household detergents,
bleaches, drain cleaners, and other household
chemicals can be used and won't stop the
bacterial action in the septic tank. But
don't use excessive amounts of any household
chemicals. Do not dump cleaning water
for latex paint brushes and cans into
the house sewer.
Don't deposit coffee grounds, cooking
fats, wet-strength towels, disposable
diapers, facial tissues, cigarette butts,
and other non-decomposable materials into
the house sewer. These materials won't
decompose and will fill the septic tank
and plug the system. To use a 5-gallon
toilet flush to get rid of a cigarette
butt is also very wasteful of water. Keep
an ash tray in the bathroom, if necessary.
dumping grease down the drain. It may
plug sewer pipes or build up in the septic
tank and plug the inlet. Keep a separate
container for waste grease and throw it
out with the garbage.
If you must use a garbage disposal, you
will likely need to remove septic tank
solids every year or more often. Ground
garbage will likely find its way out of
the septic tank and plug up the drainfield.
It is better to compost, incinerate, or
deposit the materials in the garbage that
will be hauled away. As one ad says, "You
can pay me now, or pay me later."
a good quality toilet tissue that breaks
up easily when wet. One way to find out
is to put a hand full of toilet tissue
in a fruit jar half full of water. Shake
the jar and if the tissue breaks up easily,
the product is suitable for the septic
tank. High wet-strength tissues are not
suitable. As long as the tissue breaks
up easily, color has no effect on the
septic tank. Many scented toilet tissues
have high wet strength.
your septic tank every one to three years.
How often depends on the size of the tank
and how many solids go into it. A rule
of thumb is once every 3 years for a 1,000
gallon tank serving a 3-bedroom home with
4 occupants (and with no garbage disposal).
Here is a word of caution: Never go down
into a septic tank. The gases present
may poison or asphyxiate you. Only trained
professionals should enter a septic tank
or any other confined space.
properly clean a septic tank, the manhole
cover or the tank cover must be removed.
This is the only way to be sure that all
the solids have been pumped out. A septic
tank cannot be cleaned adequately by pumping
out liquids through a 4-inch inspection
pipe. Doing so often results in some of
the scum layer plugging the outlet baffle
when the tank refills with sewage. Be
sure that the tank is opened when it is
cleaned. At this time the baffles should
be inspected and replaced if necessary.
wastes from a properly operating water
softener will not harm septic tank action,
but the additional water must be treated
and disposed of by the drainfield. If
the softener recharge overloads the sewage
system, this waste water can be discharged
to the ground surface since it contains
no pathogens. But it must be discharged
in a location where it will not be a nuisance
or damage valuable grass or plants.
Using too much soap or detergent can cause
problems with the septic system. It is
difficult to estimate how dirty a load
of laundry is, and most people use far
more cleaning power than is needed. If
there are lots of suds in your laundry
tub when the washer discharges, cut back
on the amount of detergent for the next
similar load. It's generally best not
to use inexpensive detergents which may
contain excessive amounts of filler or
carrier. Some of these fillers are montmorillonite
clay, which is used to seal soils! The
best solution may be to use a liquid laundry
detergent, since they are less likely
to have carriers or fillers that may harm
the septic system.
Each septic system has a certain capacity.
When this capacity is reached or exceeded,
there will likely be problems because
the system won't take as much sewage as
you want to discharge into it. When the
onsite sewage treatment system reaches
its daily capacity, be conservative with
your use of water. Each gallon of water
that flows into the drain must go through
the septic tank and into the soil absorption
unit. Following are some ways to conserve
water that should cause little hardship
in anyone's standard of living:
Be sure that there are no leaking faucets
or other plumbing fixtures. Routinely
check the float valve on all toilets to
be sure it isn't sticking and the water
isn't running continuously. It doesn't
take long for the water from a leaking
toilet or a faucet to add up. A cup of
water leaking out of a toilet every minute
doesn't seem like much but that's 90 gallons
a day! So be sure that there is no water
flowing into the sewer when all water-using
appliances are supposed to be off.
a water meter is a sure way to know how
much water you are using and how much
the water use will be reduced by doing
certain things. A water meter for a home
should cost from $50 to $100 plus installation.
most effective way to reduce the sewage
flow from a house is to reduce the toilet
wastes, which usually account for about
40 percent of the sewage flow. Many toilets
use five to six gallons per flush. Some
of the so-called low water use toilets
are advertised to use only 3.5 gallons
per flush. Usually the design of the bowl
hasn't been changed, however, and often
two flushes are needed to remove all solids.
That's seven gallons! Toilets are available
which have been redesigned and will do
a good job with one gallon or less per
flush. Using a one-gallon toilet rather
than a five gallon toilet will reduce
sewage flows from a home by about a third.
This reduction may be more than enough
to make the sewage system function again.
While prices may vary, one-gallon toilets
can usually be purchased in the $200 range,
far less than the cost of a new sewage
a water meter you can determine how much
water your automatic washer uses per cycle.
Many washers now have settings to reduce
the amount of water used for small loads.
Front loading washers and suds savers
use less water than top loading machines.
If your sewage treatment system is reaching
its maximum capacity, try to spread the
washing out during the week to avoid overloading
the sewage system on a single day.
and showers can use lots of water. "Setting
up camp" in the shower with a shower
head flow of 5 gallons per minute will
require 100 gallons in 20 minutes. Shower
heads that limit the flow to 1.5 or 2
gallons per minute are available and should
be used. Filling the tub not quite so
full and limiting the length of showers
will result in appreciable water savings.
the water from the faucet cold enough
to drink? How long do you let it run to
cool down? Keep a container of drinking
water in the refrigerator. Then it won't
be necessary to run water from your faucets
in order to get a cool drink.
There may be other ways to conserve water
that you can think of in your home. The
main idea is to consider water as a valuable
resource and not to waste it.
Following a few simple rules like not
using too much water and not depositing
materials in the septic tank that bacteria
can't decompose should help to make a
septic system trouble-free for many years.
But don't forget the septic tank does
need to be cleaned out when too many solids
build up. Septic tanks need tender, loving
| 6.Septic Installer